Style XP seems to clunky to me, not to mention they still attach 3rd party junk (spyware) to some of their themes even if you pay for it. Windowsblinds has gotten much better and uses much less resources than older versions. I use neither.
I went to Belchfire.net
and installed the "multi-patcher". It replaces the uxtheme.dll allowing you to install unsigned visual styles and themes within Windows without having a 3rd party app installed.
Here is the link for the Multi-Patcher
The patcher is free though they do have a pay product as well. Use the multi-patcher, it's nice. They have a full tutorial explaining it all and allot of nice themes and styles. You can use themes and styles from almost
anywhere if you don't like the ones on Belchfire so long as you can extract them properly.
Here's the tutorial
for installing visual styles and themes once you have the "multi-patcher" installed.