Style XP is not a skinning engine. It uses Microsoft's built-in visual style engine, but enhances it by providing many useful tools. Style XP can import, select, rotate, and manage themes, visual styles, wallpapers, logons, bootscreens, icons, and explorer bar. Future versions may support sounds, cursors, screensavers, and packages of all the above. How does it work? Instead of lines and gradients, the XP user interface natively supports the use of skinned bitmap controls (a visual style). This is Microsoft's own innovation. Style XP includes its own visual styles.
Tools and Utilities
Product page: here