OS? Need Windows or not?
Anyway, budget eh?
AMD Athlon II X2 240+ ECS A785GM-M5 - $178
2GB DDR2 800MHz - $65
Hitachi 500GB SATA HDD - $75
AcBel E2 470W - $65
PowerColor HD4670 - $120
DVD Super Multi - $34
PowerLogic ATX casing - $40 (Look around for other cheap ones
too)
Total WITHOUT OS: $577
Cut down on so many corners already, cheapest I can make. If you
want with OS, no hope already. OS already $100+. You want it to be
future-proof, you gotta spend about $650, switch to DDR3 based
motherboard. The HD4670 is decent enough, might be okay for high
settings depending on the game.
Gaming PCs don't actually need a DVD drive i guess.
Look to Nvidia Geforce maybe better?