taking this athlon 64 as a reference is no good idea imho - i doubt the 64bit make much of a speed difference at a game like doom, apart from that you can always bring every pc to itβs knees with the right settings. my old geforce 2 gts which was enough to play rtcw and et at and every current game at high settings with good framerates and i am sure my geforce ti4200 will be enough to play doom3
what most people donβt understand is that itβs not high Mhz or the newest graphics card that make a game run well, youβd wonder what can be achieved when you build a good system (no cheap all in one offer from the next cheap market but every part wisely considered) install the right drivers and do a proper configuration!