Gotta love that. Dell and Alienware selling 4gig+ ram laptops with an OS that can only run 3/4 of it.
I got 2 gigs, and I never used it all at once, even when running and going between like 10 applications (I've gotten close though :) ). 4 gigs is kinda pointless unless you're doing some real intensive back-n-forth stuff.
RAM is only short-term memory, it doesn't spontaneously make your computer faster like many people seem to think.