I expect.
UT03 and UT04 have same engine but UT04 has higher requirements.
Do you even know most wanted requirements?
if a fx5700 plays it at 640*480 low that too only 25fps, then you need a geforce 6600 class to make it playable at those settings, right?
I too think that a fx 5700 should be capable of atleast 800*600 low to med at the very very minimum, but the starter of this thread tells otherwise, he has that config.
I would say that if you want an economical solution to play todays games and this as well, go for
amd 64bit 3000 venice : sub 5k
asus a8n e: around 5.5k maybe a tad more like 5.7k
1gb X 2 ram
1800XT from abroad, or 7900GT at min from here for 17k
this will be the minimum for max settings at 10X7, I hope that it doesn't take anything higher than this
but if you are really crazy about the game then wait for conroe and dx 10 cards, conroe will perhaps be better for this game as well.