[Pan]

windows NEEDS to be re-installed after awhile. Google it.
Other than that grab oodefrag run it (it has a trial) find a program called ccleaner (crap cleaner) run it. delete fonts you don't use, and uninstall programs you don't use. google speedup windows....there is a lot of help on it and most is worth something. If you are uncofortable with computers though don't use any of the registry hacks unless you really know what they do.
easy peasy
oh run a program called S&d Spybot, install a good anti-virus, then a good firewall....mostly to check what is trying to connect FROM your computer as opposed to TO your computer. Download and install Nod antivirus run it when i scans your whole computer delete it and install avast home edition, its free an very good...nod is better but costs money. The install comodo firewall, its free as well. Install these after you have checked for spyware and virii...grab a program called hijack this, run it and post the results to their forum, if there is a problem in its output...trust me someone will let you know.

if you have any more questions just ask....