4GB of ram is nice, and with today's prices you might as well - however 'only' 2GB isn't a problem. If you take a little look at RAM usage when loading up a new game, Far Cry 2 for example, you'll find it'll fill maybe 1GB but rarely any more. Leaving another GB for everything else, which is more than enough.
Of course this isn't great future proofing, but don't feel it's a big problem if you can't stretch to 4GB.
I have 4GB, and more would be helpful, but then I work with massive Photoshop files on a daily basis and a fair amount more apps at the same time (Safari is using 550MB RAM atm :schwitz
. For normal desktop use you're not going to encounter this problem.