Fact is, One gig will suite you fine. Look at my specs, 1 GIG with a GT (2 512 sticks), and I play BF2 with:
All setting high except lighting, average 78FPS, peak at 98 and low is 39.
That's great IMO, give or take a couple frames and you will be fine. There is NO WAY a game is going to demand 2 gigs of ram to run it anytime soon, they just plain won't make money.
Sig removed due to foul language. Please read the rules regarding the allowable content of sigs before reposting your COMPLIANT sig.