some form of asus board, the p5k seems nice, a core 2 duo, 2 gigs of ddr2, geforce 9600gt, 120gb+ sata drive, and w/e case/cd drives u can fit in ur budget still.
or you could go with an nforce 7 chipset w/ the geforce 7 onboard vga. throw in a nice dual core amd w/ 2 gig of ram and a hard drive or 2 and u’ll b set.