Here is a link to a really good tweak guide for Windows 7 operating system:

http://www.tweakhound.com/windows7/tweaking/index.html

Before you start implementing any of these tweaks. Read the article a few times to understand what the tweaks do. Also, BACKUP your existing system if you do implement them.

They do work and I have used quite a few of them over the years on my system(s).