I have an copy of XP I can install or I can purchase a copy of Window 7 if need be. Which would everyone recommend? Most just setting this up to play games, I've got a laptop for everything else.
VGA EVGA 512-P3-N801-AR 8800GT 512M
PSU OCZ|OCZ700GXSSLI 700W RT
CPU AMD ATHON II X3 440
MSI 870A-G54 AM3
MEM= 2GX2 GSKILL F3-12800
Roswell Destroyer case
2 160G 7200 HHD
+1 on the Windows 7 x64. With 4gb of memory you will be much happier using it all
You might want to pick up a Samsung Spinpoint F3 500gb HD to put it on as well. Only $54 at newegg and it will be 3 or 4 times faster than those old 160gb designs even if they are in RAID. I still have my 2 x 160gb Seagate drives from back in the Pentium 4 days. 1 in an external enclosure and 1 in my case as backup.