ditto on what AR & SeanC Said (Just curious, up there, do you have many people mis-pronounce your name too? Same first name here, just have so many people who know who Sean Connery, Penn, Young, Bean etc are, but can't seem to pronounce the name when us "normals" have it, always pronounce it Seen instead of like Shawn?)
anyways, yeah 2GB will be fine, as SeanC said 3 will do too, but I'm running 3GB & XP, when I bumped up my RAM from 2 to 3, I didn't see any kind of performance jump from what I had before for games or regular apps & programs.
however the reason I did that wasn't for normal apps, but as additional RAM for a few extra apps/programs I run, mainly a couple of 3D Graphics programs, which I did see a slight drop in render times, but got the extra RAM so those can use more while the rest of the system still had some to use.