Microsoft's upcoming operating system, Windows 7 is now available for free. Before you get too excited, it's not a final copy, it's a Release Candidate, which means you're helping them test an unfinished operating system. It might not be 100% compatible with the software on your computer, so if you do plan on giving it a shot it's probably best using your home rather than your work computer.

Early tests show it's a pretty stable version and worth trying out. It appears to run better than Vista and has some improvements that promise to make it a popular operating system. The scheduled release date seems to be the Fall, but you would be able to test it out for a while after the release date. 

The Release Candidate will expire on June 1st 2010, but two months before it will shut down every two hours.  Not the greatest news I've heard, but it will give you plenty of time to pick up a retail copy if you decide to upgrade.

Download it here.