Personally, I'd stay away from iBuyPower and PowerPC (I'm fairly sure they're part of the same company). I bought a computer from them on Newegg (the computer I'm using now) and the motherboard and RAM both had issues with it; I email to see what I should do (having done everything in my fairly extensive knowledge to test both parts beforehand and coming up with some pretty bad results) and get a response a week later, my next email was met with a two week response time and I just got fed up with it. After looking into the issue, I found I wasn't the only one with similar issues (and they've had numerous complaints from the Better Business Bureau.)
If you want a computer that's within a $1000 price range from them, yeah, you'll probably regret it and end up having to replace pieces of it as you go (or face a couple weeks without a computer as they ship you a replacement). They're EXTREMELY hit-or-miss. I did, however, like the clean install (without the trashy "HP/Gateway/etc junkware") and it ran beautifully until I started getting bluescreened by junk parts.
To be honest, I was intending on replacing it piece by piece as I went (I now have a nice motherboard and a new pair of 2GB sticks in it, and room for two more where I didn't have before) but I didn't plan on having to do it so soon. My next piece will probably end up being the video card, or perhaps the processor... but first I'd likely look into a bigger power supply, and maybe a slightly more robust cooling system.