I would agree with Oregon - If you're going to spend 2-300 why not buy something new. I personally would get a Dell Vostro (small business line) desktop. They frequently have specials in the 400 range (easily back into the 250-300 range once you sell off the monitor). Granted.. you'll never overclock with that rig but the c2d will be much faster, and you get quiet a bit more for the money - and a warranty.
http://www.dell.com/content/products...243&lid=507235
Core 2 duo
2GB Ram
20" LCD
250 Sata HD
DVDRW
Free Shipping
OS license
1yr warranty
for $489.00