http://www.tgtsoft.com/downloads/uxthemepatcher.zip
Download this and follow these directions so that you don't have to pay for the Style XP program, but still be able to use all sorts of themes. Follow these directions for this to work.
First uninstall StyleXP and reboot. (Don't worry, your favorite themes will still be there.)
Run the "uxthemepatch.exe" and go to C:windowssystem32dllcache (to reach this folder you'll probably have to type out the address in the windows explorer location bar).
Locate "uxtheme.dll" in this folder and rename it "uxtheme.bak".
In C:windowssystem32, also rename "uxtheme.dll" to "uxtheme.bak". Right next to it should be "uxtheme.pat", the file which was created by the .exe you ran a minute ago.
Rename the .pat to "uxtheme.dll", answer "cancel" then "yes" to any warnings from Windows and reboot.
Restart your computer and right click your desktop and go to "properties" and change to your favorite theme.
Smile because you just saved $20