ok guess i better upgrade my wanky geforce FX 5200 coz i wanna play doom3

want something with LOADSA memory (256+mb) n does all the difficult stuff with ease (ie antianalysing, bumpmaps, alpha blending etc. etc. also would like it to do 8+ passes per frame minimum. basically one that'll run doom3 well (bearing in mind doom3 shades each individual pixel in each frame, so eats GFX cards for breakfast