Bench-marking, even two exact computers, will cause different results. If you want to keep your system sweet, un-install ALLL the crap that you are never going to use.
Eg: MS-OFFICE is fast approaching a gig, and you can type anything you like using
NOTEPAD, (For HTML), and WORDPAD.
The only advantage to having plenty of MEMORY, is that WINDOWS can store more programs there. It takes a lot of time to keep all them cells refreshed. And it's still got to switch/look-up the programs anyway...
XP itself isn't worth mentioning, as MS-DOS, did nearly the same things, with a 6MB (OS). Go figure...