Go to download.com and download ccleaner [i recomend this to everyone] and install it make sure you don't tick the cookie box tho and go on windows run the cleaner delete selected files and do the same again but for aplications then go on issues and press scan delete files and don't back up to registry then it should be free of all the junk you have collected.It wouldn't do any harm to run a spyware scan.an anti-virus scan and then defrag then you will have a nice clean computer.