i think that the 3 gig limitation is actually due to physical limitations (only 2 slots and one of them has an integrated 1gig from the factory). and yes, 2 gig is nice but when you work with CS2 + firefox and maybe itunes in the background, 2 gigs run out real fast.
Hm, I work with CS2 and Firefox and am fine. I do use Winamp though, which I think (don't quote me for this) is less of a resource hog then iTunes.

