Windows Vista comes with a free 30 day trial. But there is a trick you can use to extend this trial 3 times. If you extend at the end of the 30 day period (when you only have 1 day left), you could end up with 120 days of free Vista usage. Here's how to do it:

- Type cmd in the Start menu search box, and then hit the shortcut Ctrl+Shift+Enter to launch it in admin mode.

- At the prompt, run this command: slmgr -rearm

- Windows will spin its wheels for a while and then tell you that you need to reboot. Once you reboot, your trial will be back to having 30 days left.