You may be getting tired of the default theme in Windows Vista, and luckily for you there is now a uxtheme.dll patch for Vista. Visual styles kept XP alive for me and many others over the years, so I'm looking forward to a new generation of themes. Unfortunately there aren't too many themes for Vista currently, but in time there will be.
Download: Windows Vista uxtheme.dll Patch
Are you tired of Vista's Aero theme?Downloads and detail install instructions can be found at Lis Killer's blog
A patched uxtheme.dll gave you the freedom to use un-signed custom visual style in Windows XP but in Windows Vista you have to replace three dll files to use third party visual styles.
Those three files are uxtheme.dll, shsvcs.dll and themeui.dll
Download: Windows Vista uxtheme.dll Patch
Nicholas Alston