Please note that you're doing this on your own risk.
Download Neowins UXTheme Multi-Patcher and run it:
http://www.softpedia.com//progDownload/UXTheme-Mu...Download-2369.html
When you get asked to restart your computer, do so. Now you can use unsigned themes on your Windows copy without using any software at all. These themes are called msstyles.
A great way to find msstyles is to search on DeviantArt.com:
http://search.deviantart.com/?section=browse&q=msstyle
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