According to Microsoft you will still see an improvement going from 2 to 4 gigs on 32bit. Even though it does not show up, the operating system is still utilizing the additional ram (according to MS). I am running 4 gigs on 2 machines 64 and 32 bit versions of Vista. I am thinking about going to 8 gigs on the 64 bit machine since it is so cheap right now. I still use a 2gig swap file with 4gigs and would like to completely eliminate it.