I bought a gateway fx desktop for just over $1000. It's got an intel Q9300, 4 gigs ram, 8800gt, and 640GB HDD. This is the first gaming machine I have ever owned, and so far it is glorious.
I downloaded a bunch of demos. Crysis looks great, I just didn't find it all that fun. I had played through COD4 on 360, and just now played the PC demo. It's like I'm playing a completely different game. It looks fantastic, and mouse/keyboard control is so much more accurate than a controller.
It's nice to be able to crank all the settings to max and just have everything run great. I know I probably could have saved money ordering online or building my own, but at least I got what I wanted, and can finally participate in PC gaming.