In Vista, you might have seen a feature which shows the thumbnail preview image for each task in the Windows Taskbar. There’s a small utility known as Visual Task Tips which does the same in Windows XP. It’s just 100kb in size and is very light on resources.
You can download it from below. To install it just double click on the installer and reboot. Now just move the cursor to any task in taskbar to see the Visual Task Tips in action.