The article below, was written as a response in the forums to a user, who was asking for advice on how to speed up his PC which had over time become noticeably slow.
It's based on Windows XP. The accompanying video above, though was done on a Windows 7 system. Some few things like the names of some components or items are a bit different, though if one has some PC experience or after taking a good cup of coffee, as you work, you will note a lot is not that different at all.
So here is an updated version of the original Windows XP based article, explaining how YOU can do this YOURSELF: