WindowBlinds can customize the look and feel of Windows XP.

It's a Windows utility that enables users to personalize nearly every aspect of the Windows graphical user interface. It can "skin" your title bars, push buttons, Start bar, radio buttons, and nearly every other part of Windows. There are thousands of freely available skins to choose from. Use WindowBlinds to make Windows look like another operating system (Mac, Linux, etc.) or give it your own unique look and feel. You can also create your own skins using the freely available SkinStudio. WindowBlinds eliminates the need for any stay-resident program making it use virtually no extra memory. It also makes use of hardware acceleration found on most nVidia and ATI cards resulting in an overall performance increase.