512 i assume?
i was playing with 1 gig for a while, and i actually noticed a performance DECREASE!
If i were you, i'd snag some dual channel high quality (good timing) ram.
that $50 512 stick from frys wont cut it. You are going to have to bite the bullet and spend about 90-$120 for the good stuff.
personally, i chose OCZ ram, dual channel 3200, gets me about 17000 in 3dMark2001 SE
(the 1 gig with a crappy 512 stick was getting me about 12700)
If i were you, i would go to www.newegg.com and pick up 1 gig dual channel Crucial pc3200. I think they have it for about 130 right now. Well worth it in my opinion.
(as it is, make sure vsync is off, will boost your fps DRASTICLY)