1st thing, download ccleaner (
http://www.filehippo.com/download_ccleaner/)
in tools and advanced deselect "temp folders older than 24hours"
run the cleaner tools, selecting as many options as you want
Do the same with the registry tool (make a backup when prompted on the 1st run) you will need to run it several times.
next click start run and type "msconfig" select the startup tab, using
http://www.bleepingcomputer.com/startups/ go through and remove the un-needd ones...which will be pretty much all of them apart from AV programs (print screen and send me the list and i will tell you what to leave checked if you want)
once finished select exit without restart
next click start --> run and type cmd (if using vista or win 7 run this as an admin) then type "chkdsk /r /f" and presss enter, then type "y" and enter again and restart your machine.