The game should run ok (30 fps) with all settings maxed out. Carmack said something like the full experience target of doom 3 was the geforce 3 class cards, and the minimum card was a geforce card. So I hope to run this game and the others that uses this engine with a geforce 4 at 1024 and all settings maxed out, without AA.
And the light system of the game is the greatest improve of the engine , if you turn it off, u will lose the greatest aspect of the game.
I dont know anything about the cpu required...(1.6G or more maybe???)
athlon xp 1.8+, asus a7v 266e, 512 ram, pny geforce ti4600
Sorry for my english