There is a various Windows XP themes available for download. If you wanna modern Ubuntu look for your Windows XP continue to read this tutorial:

1. Download skin file from here. The size is 2.3 mb and it includes pretty much anything you need to make your Windows computer look like the Ubuntu operating system. Besides the graphic elements such as wallpapers, fonts, cursors and icons, you also get a special DLL patcher that enables you to use the theme even if it’s not an official Windows visual theme.
2. Unpack the file and run UXTheme Multi-Patcher, and patch Windows XP, so you can apply the new themes
3. Then copy ubuntu folder to /windows/resources/themes/ and double click on Smooth Ubuntu.theme
4. That’s it. Enjoy in you new Ubuntu flavour Windows XP theme

Tags | Howto, Look and Feel, Tutorials, Windows XP