Fast computer becoming slow

Archived from groups: microsoft.public.windowsxp.perform_maintain (More info?)

hi all, i got my computer May 2003 around 1.5 yrs ago, when i got it, it was
brand new. But now it is becoming very slow, freezing often and many programs
arent responding. This is really frustrating. Also it has been affected with
spyware so i downloaded a microsoft program (Microsoft Anti spyware), it got
rid of all or most spyware but i think there maybe 1 or more still on there,
when i start up internet explorer it automatically goes to a site
"www.jetsearch.com" and i have to stop before the page loads other wise pop
ups come up saying you computer could be infected and sometimes even changes
my wallpaper and i have to do a system restore to fix it. i try to reset the
homepage but i keeps changing back to the jetsearch website.

Any ideas on both problems would be appreciated, thank you