Desktop themes give Windows XP a beautiful design: Window framework, character sets, wallpapers, icons, screensaver and more – all this you can adapt to your own taste and combine in theme packages. These can be selected then in the desktop characteristics under designs. In the web there is a large fan community, which offers such themes free of charge, for example under www.themexp.org. But it is not as easy to install these themes. Usually the shareware Style xp (20 dollars) is recommended.
It is also possible free of charge: For the themes the file uxtheme.dll is responsible. You find it in the directory system32, and have to change it. Because it can be changed under the running windows, you should for safety reasons first create a copy, to example in c:\data. This original file you will later – if necessary – write back. Create a second copy for the changes, to example in c:\newtheme. Now patch this copy with a hexeditor,for example with Xvi32.
You start Xvi32, open c:\uxtheme.dll, then select then search/replace and replace 81 EC 80 00 00 00 56 57 by 33 F6 8B C6 C9 C2 08 00. It occurs exactly once. Store the patched DLL. The changed file you have to copy into the system32-directoty. The original will be overwritten.
Then you boot from the windows XP-CD and press [R], in order to start the re-establishment console. Start as administrator and enter copy c:\uxtheme.dll c:\windows\system32\. Confirm the overwriting of the file. Exit the console. Windows starts again.
Now download a few themes from www.themexp.org and copy them unzipped to c:\ windows\resources\themes. In this directory for each theme there must be an own theme-file. There resources are stored as pictures, icons and so on.
The themes you can call under desktop characteristics and designs. The Patches are the same windows XP, SP1, SP 2 und Windows servers 2003, but in other places in the uxthemes.dll. Very helpful is the tool ThemeMultipatcher.