|"What are the changes when using TweakUI?"|
There are no changes unless YOU make them! When you install TweakUI it will be listed under Start > All Programs > PowerToys for Windows XP. Click the TweakUI icon & when it pops up, you can decide for yourself what you want (or don't want) to change. But as I said, no changes are made unless YOU make them, then click APPLY.