As you navigate through the many categories, just know that any change you make can be undone by simply reversing the step in which you made the change. In most cases, a change is made in just a couple of mouse clicks.
There are many useful tweaks that aide in the customization of the operating system to create either better performance or improve functionality. But, since tweaking is more of a personal preference, I will leave it to you to explorer the hundreds of possibilities on your own. Click the following link for a free TweakUI download for Windows XP:
http://www.microsoft.com/windowsxp/down ... rtoys.mspx