Sure you have ever installed any program using Microsoft Windows Installer. In case an error ocurrs during the installation, all that information is saved and stored, occupying beloved space in your HD.

Now you can get rid of that information and set some MBs free.

Windows Installer CleanUp Utility is the application you need to delete that data and free up your HD.

Download and install it and save MBs and even GBs. However, be careful when using it, if you don't take care, you might delete things you shouldn't.

If you want to have Microsoft Windows Installer like the first day, Windows Installer CleanUp Utility will be really helpful.