Microsoft offers several PowerToys for Windows XP as a free set add-on to enhance the operating system. Some of these are add-ons are more useful then others, for example Tweak UI allows you to modify certain aspects of the OS. Other add-ons Alt-Tab Replacement, are a little less useful in my opinion.

Note: These tools are unsupported by Microsoft, so if you have any problems you're on your own.

    * ClearType Tuner (New): Allows you to tune the ClearType technology to make it easier to read text on your screen.
    * HTML Slide Show Wizard (Updated): Creates an HTML slide show of your digital pictures, ready for your Web site.
    * Open Command Window Here: Provides a quick way to open a command window.
    * Alt-Tab Replacement: Displays the icon of the application window you are switching to, you will also see a preview of the page. This helps particularly when multiple sessions of an application are open.
    * Tweak UI: Grants you access to system settings that are not available in the Windows XP default user interface....

    * Power Calculator: Graphing calculate that can evaluate functions, perform different types of conversions.
    * Image Resizer: Allows you to resize one or many image files with a right-click.
    * CD Slide Show Generator: View images burned to a CD as a slide show.
    * Virtual Desktop Manager: Manage up to four desktops from the Windows taskbar.
    * Taskbar Magnifier: Magnify part of the screen from the taskbar.
    * Webcam Timershot: Allows you take pictures at specified time intervals from a Webcam connected to your computer and save them to a location that you designate.