To speed up slow running PC will not be tough any more! If you can find the proper program that best fit your system(without cost you much money), your PC will run like a new one again! My friends recommend me to read this. It is useful for fixing slow running PC. YOU CAN HAVE A TRY!
http://ezinearticles.com/?Windows-XP-Runs-Extremely-Slowly?-4-Easy-Ways-to-Make-it-Run-Like-a-New-One-Again!&id=3579973
Lily, January 2010