Turning off XP's unnecessary services does wonders. It takes a little time but it's well worth it in terms of better system performance and online security.
There are numerous guides online for which services to turn off, which to set to manual and which to leave on automatic but I've found Black Viper's site
the easiest to use.
Have you scanned for spyware? If not, download, install, immediately update
and then run Spybot
. Read the help files to familiarize yourself with how they work. I recommend you use them both since each tends to find things the other misses. Let them clean up any spyware found.
Then, to be doubly sure, download and run CWShredder
(link to the download is near the bottom of the page).