The display of thumbnails of open windows in the taskbar is a new feature that was introduced in Vista. Visual Task Tips is a small program that lets you do so in XP. If you want your XP look like Vista, then you need this software.
For more details, watch this trick: Put a look at Windows Vista to XP.
Related software : Taskbar Repair Tool Plus! , Google Desktop , Animated Screensaver Maker , Transform XP to Vista .