2 gigs is fine for ordinary use. I don't know anything about gaming, but I do have 2 gigs on my Vista laptop and it runs well. Be sure to disable all the junk running in the background, as that'll slow down a machine no matter how much RAM you have.
Don't be alarmed at what seems like high memory usage. Vista uses as much memory as it can all the time. That's how it's designed. If a program needs more RAM, Vista discards some of the no-longer-needed stuff in RAM.