Please don't buy this computer. I did. I was a 'switcher' and spent a small fortune on it and the 30" monitor and lots of upgrades like RAM and HD. I have an Apple G4 powerbook that is wonderful though let me say!
But this DP 2.5 G5 is a dog, a very expensive dog. It has never worked properly from day one. The dealer i bought it off is useless. Apple Australia don't care one bit. It took 6 weeks to fix a broken ethernet port!
I wanted a really good computer and did a lot of research. So i went top of the line and got this new G5 power mac. I wished i hadn't. I don't know that much about computers, i would say my knowledge is moderate, but i don't want to know a lot - it is meant to just work and make things easier, not harder. This computer does not. You will see lots and lots and lots og glowing reports from apple and apple sources. Don't believe the hype. I have had to reinstall the OS twice and it still doesn't work properly. Every apple software upgrade creates a new problem.
Ready for this - for all of apples claims about stability and 'built on unix' marketing puffery, my xp pro at work would be 20x more stable. Seriously. And IMHO with some experience of these guys, i would never never never get an apple in a corporate/working enviroment. Great for home, my powerbook is fabulous, but they just don't have the customer commitment for a work enviroment. Not a clue.
The list of problems could go on and on and i have thought long and hard about posting, but i use these posts and appreciate honest feedback.

This computer is so quiet, you have to check it to see if it is still running. I am an daily Photoshop user since 1987, and a loyal Mac user since 1984 (I've worked for Apple, IBM and Motorola). This system is so fast, it will keep up with everything you can throw at it in Photoshop CS2 - no delays - just instant filtering. The last Photoshop job I did (resizing and filtering 96 photos), I could really see the time saved using this computer - about 30% over my older G4 - which spells productivity. I ordered this system as a reconditioned unit for $2299 from the Apple Store with free shipping (53 lbs), and got a free upgrade from the 160G to 250G Hard Disk and Tiger DVD in the box - both were unexpected, plus a full warranty just like a new system. The system appears to be brand new, probably an open box or returned system. I added 2G more RAM for $200 for 2.5G total. Some reviewers have been critical about the lack of ports on the G5 systems (if that is all they can find at fault), but if you need more ports, you can easily add in a 3 USB 2.0/2 Firewire PCI card from IOGear for only $38, or a 4 port USB 2.0 PCI card for about $20 - so stop whining about ports. The rear Firewire 800 port really screams with my LaCie Firewire Backup Drive, which is another reason to upgrade to the G5. Unlike the new 2.7GHz system (only 8% faster for $3000), the 2.5GHz system comes with one ADC and one DVI port on the 9600XT video card, plus a DVI to VGA adapter in the box. The new G5 systems don't support ADC without having to buy a $99 DVI-ADC adapter, which is messy to hook up, requiring a power supply. One more reason for buying the older 2.5GHz model if you own an older ADC LCD display (clear plastic model). Overall, I am very impressed with this 2.5GHz MP system, and can see this system lasting many years. XBench speed score is a fast 252.

I've been a Mac user for nearly 20 years. In May of 2004 I upgraded from a 450 MHz G4 (512 MB RAM) to a dual 2.0 GHz G5 (1GB RAM, two 250 GB hard drives). The machine I bought was defective-all nine fans were going full blast all the time. The operating system and software worked fine, but the tower was intolerably loud (it really sounds like a car the way the fans fire up). I spent about 45 minutes on the phone with Apple tech support. The fellow I spoke to was helpful and friendly until he misguided me about pressing a tiny button in the innards of the machine too many times (it's been a year, I don't remember what exactly this little button resets). He instantly became accusatory, telling me I didn't follow his direction and refused to discuss it. He basically told me my computer was hosed and that I may have voided the warranty; I should bring it in to be serviced and not turn it on again. The guy really turned into a jerk. I suppose he was just trying to cover his ass.

I turned the machine back on and it ran just as before. Fine, but loud. I took my machine to the Apple Store in San Francisco for diagnosis, and they confirmed there was a "thermal" problem. I was a part-time student at the time, bought the machine through school and though it was eligible for replacement, I couldn't exchange it directly through the Apple Store. Fortunately, in the time it took Apple and my school to acknowledge that I had a defective computer Apple announced the dual 2.5 GHz, so I was given the option of a partial refund, since the dual 2.0 GHz had gone down in price, or a free upgrade to the dual 2.5 GHz. I went for top-of-the line in the first place (with a 23" Cinema Display HD) with the idea that I wouldn't be buying another computer for a good number of years. I had to wait about four months for the dual 2.5 GHz after they were announced (they let me keep the defective one in the meantime), but it was definitely worth the wait. And this is exactly what anyone should expect after dropping $5,000 + (with the display and software).

The dual 2.5 GHz runs amazingly quiet (when it really needs to think, the fans fire up, but they typically aren't audible for long). The increase in speed (for me) was amazing. The applications I use most often are: FileMaker Developer 7 , Omni Graffle 3, Virtual PC 7 (for testing), Dreamweaver MX 2004 along with Apple's standard mail, text and web browser apps. I'm also increasingly using Final Cut Pro HD, which I think you'd only really want to run on a machine this fast. With the occasional exception of Excel, I don't have a need for Microsoft apps.

The G5 is on nearly 100% of the time, since I sometimes need to access it remotely, and yes, it's crashed a few times, but this is really quite rare. Tip: I've found the best way to tell if a Mac has crashed or is just frozen is to set the clock in the menu bar to display the time with seconds. If the clock has stopped ticking altogether, it's a good indicator that the system has crashed. Otherwise, it's just frozen, so tricking around with it (force-quitting applications or putting it to sleep and waking it back up), tend to bring it back to life. Again, this sort of behavior is rare and, as such, acceptable for me.

For PC users considering a G5, I have this to say: I've always been a Mac user, and I've always, always complained when I've had to use a PC. I'm not snobby about it; I'm just accustomed to very well-designed and integrated products (I drive a Porsche 993, and I'm as passionate about its design, especially its clever temperature controls and cruise control). That said, using VPC (Virtual PC) on my G5 has really given me a different perspective on Windows. I actually LIKE using Windows...as long as it's on my G5. This is largely because of my Apple keyboard and the 23" display, which just make for a better Windows experience. You can run VPC to take over your whole display, or run it within a window as if it were any other app on your Mac. I have a Microsoft 5-button, scrolling optical mouse that I've had for over 5 years (it's great). Right-clicking works without installing any drivers, in both Mac OS X and Virtual PC. I use Windows 2000 Pro, and my colleagues would be surprised to hear I'm actually looking forward to upgrading to XP. Windows isn't as zippy as running it on a top-of-the-line PC, I suppose, and it hangs here and there, but for my purposes it works perfectly. I don't think it's a great idea to run Windows in VPC as your "primary" OS, but for seasoned Windows folks who are looking to make a transition to the Mac and still want to jump back to familiar territory, I'd certainly recommend this hardware/software combo. VPC (to which I've dedicated 512K, or half of my G5's physical RAM) can be a memory hog, slowing everything down on my Mac, so if you plan to use it regularly, I'd recommend more than 1GB RAM. A couple of cool things about VPC: You can run multiple Windows OS's at the same time (I've seen, but not experienced this). You can "pause" a Windows OS so it doesn't hog memory. You can also "save" a Windows state when you quit VPC, so that when you start it up, everything is right where you left it. After too many frustrating visits to my dad's to"fix" his Windows problems, the Mac should be a compelling option for PC users. Virtual PC on this machine makes it especially so.

Bottom line: An excellent system. Advice: If you can, buy directly from an Apple Store; they're far more willing to offer support than if you buy elsewhere and bring your issues in to the store. If you buy an Apple product elsewhere to save money or support a local vendor, know that that can become a support barrier Apple will hide behind (I wish, like Bose, they'd just support their damn products wherever you purchase...it was a hassle for me). Also, don't expect, but do LOOK for problems right away, within the first two weeks. Apple is notorious for not admitting there's something wrong even when it's a known issue (like the fans on the first machine I ordered), and even then they're very reluctant to replace a product outright unless you hound them. It's easy enough to find other people with similar problems in forums and such. I'm a little bitter about my customer support experience, but in the end they got it right. I think the majority of real Apple customers don't have to experience this. I bought 3-year AppleCare, and so far, fortunately, have not had the cause to use it. I believe Apple should stand behind its products without having to purchase additional support, but Murphy's Law guided my judgment there. In any case, I'd highly recommend this machine to anyone who is considering it.

This now has become my all-time favorite system. It has dual 2.5GHz processor which adds up to 5.0GHz which no other Intel computer can compete with. 512 MB of RAM and up to 8GB which is the most I have ever seen! 160GB and up to 2x250GB which is 500GB which can save so many things. It has a DVD-R Drive which can of course burn DVDs. I love the applications on the Mac OS X v10.3 Panther and I think it beats Microsoft Windows XP Professional Edition. Here are the specifications for the Apple Power Mac G5

Processor | PowerPC G5 Dual
Optical Disc Drive | DVD-RW / CDRW Combo
Hard Drive (GB) | 160
Memory - Processing RAM included | 512MB
Memory - Processing RAM Maximum | 8GB
Memory - Video RAM | 128MB Dedicated
Connection - USB Front | 3
Connection - USB Rear | 2
Connection - IEEE1394 Firewire Front | 1
Connection - IEEE1394 Firewire Rear | 2
Connection - DVI HDMI Digital Display | 1
Connection - Sound | In/Out
Expansion - PCI | 3 Available
Connection - RJ11 | Yes
Connection - RJ45 | Yes
Connection - Video | Out
Expansion - Drive Bay Internal | 1 Available
Operating System | Apple Macintosh OS X
Ethernet Capable | Included
Software | Pre-Installed by Manufacturer
Wireless Capable | Optional
Manufacturer's Warranty - Hardware | 1 Year
Manufacturer's Warranty - Software | 1 Year

Source: www.jr.com

You should no doubt look into this computer system but if you don't want so much power (5.0GHz of it) you can go with the dual 1.8GHz processor which might suite you well.

I love this machine. It is supremely powerful, but what makes me love it is its good manners: elegant and silent. If i have a window open in my office (on a very quiet street), I cannot even tell when the computer is on, it is that quiet. Turning it on and off at the monitor is simple and calming, the whole experience of working with it and OSX can enhance your serenity. This is especially valuable when using programs like DVD Studio Pro and FCP, not to mention photoshop. I am very pleased with this computer, and recommend it to anyone.