I don't know how bad is your windows now. If you can still connect to internet, it should be ok to clean all the spyware.
first thing you need to do is to download 7 0r 8 anti-spyware from the internet.
1. yahoo toolbar with antispy, go to www.yahoo.com to download it and run it. It's free.
2. go to www.download.com and click spyware center to download "AD Aware SE", "SpyBot search and destroy 1.4", "Webroot SpySweeper trial version" and "Spyware Doctor". Download all 4 software, install and update.
3. Go to microsoft.com to download "Microsoft Anti Spyware". Install and update.
4. Go to www.intermute.com to download "Spy Subtract trial version", install and update.
After you download all the free antispyware. reboot your xp to safemode with network connection. Clean all the cookies, temp files and temp internet files. Run each software one by one, except yahoo anti spyware( it will only run on normal windows). and go to www.trendmicro.com run free online antivirus scan.
You should be fine after you use all the software.
Good luck.