ABIT KN8 Ultra Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard - $98
AMD Athlon 64 3000+ Venice 1GHz FSB Socket 939 Processor Model ADA3000BPBOX - $146
ATI RADEON 9800PRO 128M Radeon 9800PRO 128MB DDR AGP 4X/8X Video Card - $136
LOGISYS Computer Area 51 CS51BK Black/Silver Steel ATX Mid Tower Computer Case 450W Power Supply - $33.99
LITE-ON Black IDE DVD-ROM Drive Model SOHD-16P9SBLK - $19.99
(you said DVD-ROM and not DVD burner so I assume you already have a burner)

Total = $433.98

I just grabbed this stuff off of newegg. IMHO it would make a pretty good computer for the money.