As with previous versions of Windows Microsoft prevents users from using third-party visual styles with the visual style engine included in Windows 7. This is enforced by requiring each visual style to be digitally signed by Microsoft, without the signature the visual style will not be loaded. The trick to use third-party visual styles is to remove the digital signature requirement. In the past there have been a lot of tools to do this but for Windows 7 there is only one right now called UxStyle.
Getting UxStyle installed and running on your computer is easy. Just download and install from here. No more manually replacing uxtheme.dll with patched versions.
Once that have the service installed it will automatically patch the digital signature requirement in memory so you can load third-party visual styles.
The final step is to download more visual styles to use with Windows 7. Below I linked some of the best places to download good visual styles for Windows 7:
- Windows 7 Visual Styles at deviantART
- Windows 7 Visual Styles at Deskmodder
- Windows 7 Visual Styles at Neowin
- Windows 7 Visual Styles at SevenForums
Keep in mind that you can only run visual styles for Windows 7. Don't try to use Windows Vista or Windows XP visual styles, they will not load.
If you want to build your own visual style or convert a Windows Vista visual style for Windows 7 check out Vista Style Builder (it works with Win 7 now).