A lot of people mistake Vista's show of higher memory usage to applications and processes using it, which isn't completely true. Vista likes to pre-buffer some of the applications data into the memory. It's not actually in use, so windows can dump it and use that space for other applications if they start exceeding the maximum threshhold without it causing any problems for the original program or the new one, it makes programs work a bit snappier. Shut off all the extra BS like sidebar and the search cacher and turn off all the themes and you basically run enhanced XP (though I still don't like it).