EASY
Install and run these three, they are like anti virus and need the latest updates 1st before you scan.
SPY-BOT
From Here
http://www.safer-networking.org/en/download/index.html
Microsoft Windows Defender (AntiSpyware)
From Here
http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
Ad-aware 2008 Free
http://lavasoft.com/products/ad_aware_free.php
If you think it could be a virus, or u don't have an up to date antivirus, run AVG FREE
From Here
http://www.download.com/AVG-Anti-Virus-Free-Edition/3000-2239_4-10320142.html?part=dl-AVGAntiVir&subj=dl&tag=button
All of that Should remove all traces of spyware,
When you defrag, check the report for files that won't defrag, make a copy of them, it will take a while if they are fragmented into serveral pieces, then delete the original and rename the copy. Should work for all files except ones in use, search google or sharaza for moveonb.exe, Handy program to move, copy, delete files that are in use, does this at next system reboot. Careful with anything in the windows directory or subdirectorys though.
Be sure you defrag every drive/partition too.
Lastly Click start, run, then type "msconfig.exe" without quotes.
Click StartUp and you'll see most of the things that start with windows, you can untick any or all, but some programs you may have to leave running in order for them to work, trial and error.
Just reboot, and run msconfig and tick some back on at a time.
And check virual memory settings, I usually set xp to double the ram as a set size virtual memory, eg 256MB ram 512min and max size swap file.
There are other tweaks but i don't have enough time to tell you them.
Hopefully that helps you.
Hope That Helps