You will notice, but not significantly, there was a post about this a few months ago, try a search, but I find apps close down faster.
Probably 192 would be as much as you would really ever need but at the price RAM is right now 256 is the best way - make sure to get PC133 CAS 2 if possible - it's often the same price within a $ or two..
Assuming u r using Win 9x/ME