Windowblinds is a great little application that allows you to install themes for Windows XP.  It is a third party application, but it makes installing windows xp themes extremely easy, and uninstalling them even easier.

The main thing that drew me to Windowblinds was the fact that it doesn't change your core windows files like a lot of other windows theme packages out there.  It installs just like a regular application, and each theme is installed using the files from Windowblinds, so they don't directly effect your windows files.  Some of them can add or change functionality, but if you don't like what one theme does, you can switch to a different one with no harmful effects.  Want to get rid of Windowblinds entirely?  Uninstall it, and it's gone completely with no after effects.

Another thing that's great about Windowblinds is that most of the themes are created by its users, so there are new themes being created by its user base every day.

Here are a couple examples of some user created themes that resemble Windows Vista:

If you're looking for Windows XP Themes, look no further, Windowblinds is the best thing out there.  I've been using it for a very long time, and haven't found anything yet that's better.  Check it out today .

Windowblinds is actually a piece of software in a package called Object Desktop, which is a group of applications you can use to customize your desktop and make it your own.  It contains software to customize your themes, sounds, icons, menus.. you name it, Object Desktop can customize it.  Check out my Object Desktop review for more info.