Should I get an extra gig of ram? (specs inside)

E6600,8800gts 640mb, 2gb of ram. WouldI see a big difference with the extra gig or should I save money for a different upgrade?

I have a AMD with a 8600 gt xxx 256mb and 2 gigs of ram and I do ok with it.

I have heard that any more then this you don't see much of a different, That is if you are useing xp but if you are useing vista then you should get anoter gig of ram but this is just my opion. I'm no expert at all.