it did for me.....i put in 2gb more and get no more lag even on full graphic settings.
i heard though having 1gb+ gives u no or minimal lag in IF (on low/medium graphical settings)
my 'pumping' i met putting more in.
i picked up my 2gb ram for my dell (yea a dell) about 70pnds = p+p though costs vary.
i usggest you go to the crucial website and use the advisor tool to selct the right 1.
http://www.crucial.com/
though if you dont know how to fit it i recomend getting someone who does know as ram can get easly messed up if handeld the wrong way, it has alot more ways to go wrong
i personally have and Nvida 5200 128mb card in one cpu with 1.5gb ram and nvida XFX 5900 xt with 2.5gb ram and the graphics crad doesnt really make a big diff.
plus getting a new graphics card has only limited use in your computer while ram will increase everything, speed up your computer generally