Spybot Search 'n Destroy.
NOW.
[link|http://www.safer-networking.org/|http://www.safer-networking.org/]
Even if you uninstall Kazaa, you get a bunch of crap left behind - and that may be behind some of the slowness/page file nastyness. Spybot will clear out all the extra crap.
I have a red sign on my door. It says "If this sign is blue, you're going too fast."