rd2002

it depends on which os u r goin to use. for xp, i think u are fine. for vista, although it won't be slow terribly, u shouldn't expect ur pc can run as fast as u expected. also, ur pc's specification plus a video card, like u said in the thread, should be able to play games like halo 3 and call of duty 4 in low or moderate settings.
for the video card, how much is ur budget? if u have some spare money want to spend on a good video card, i will suggest hd 4850, which i think its price should around 180 usd. i am not sure the price in asia and other parts of world though...