MSDN has put up an article how to design and create colorful and dynamic icons for Windows XP. Thanks Christian.
Microsoft Windows XP introduces a new style in icon design. The following guidelines walk you through the steps of designing and creating Windows XP-style icons.Read more
The Windows XP icon style is all about fun, color, and energy—and, as there are now 32-bit versions of the icons, smooth edges. Each icon is rendered in a vector program and then manipulated in Adobe Photoshop to create a beautiful image.
These guidelines are geared towards designers. We recommend you work with a good graphic designer, especially one with experience in using vector or 3D programs, to create your images.