It's enough to do just about anything. I have 4GB and have never seen my computer use over 3 gigs. The highest it's ever used was when I ran Premier CS3 and photoshop Cs3 at the same time.
the real question is how much ram can you possibly use at once? ive never used my paging file unless stress testing my ram... 4gb is plenty. speaking of which my 32-bit OS only takes advantage of 3gb of it, and i dont think i ever maxed out my 2gb kit when i used it.