nubius - wont that lag go away though if you just diable AA? Do you play with Vsync enabled??
and if you could post what fps you get in 'Timedemo demo1 1' on (High, 1280x, 0xAA, 8xAF). im curiouse to see how much more fps you setup gets then a system i recently tested(below)
---------------------------------------
devil_warrior - i recently tested a system (xp3000 400fsb, 1gb ram, 6600gt)
but i started out with 512ddr ram originally, and with 512ram i noticed some loading pausess in Halflife2 and Doom3, sorta like what nubius mentioned, but it doesnt happen at all doors(prolly same for him)
with 1gb of ddr ram, i noticed some of the pauses went away completely and others were less noticable.... so you may be better off getting a 6800gt + another 512ddr stick of ram.
unless you can aford the ram and the ultra i guess.
when i ran Doom3 'Timedemo demo1 1' on that system i got...
High, 1280x, 0xAA, 8xAF = 51.3fps
every level of lower resolution i put it, im was able to add 2xAA and it goes same of faster... example -
High, 1048x786, 2xAA, 8xAF = 53.4fps
Halflife was easyer to run at Highest settings,1280x 2xAA, 8xAF
Note- this is always with Vsync OFF