So you downloaded the first beta version of Windows 7 when it was released to the public in January. You installed it on a separate partition on your Windows XP, Vista, Linux, or OS X box played around with it for a little while and then forgot about it. You never got around to installing the Windows 7 release candidate that came later.

Well, let me tell you what will happen the next time you boot up Windows 7 Beta. You'll be able to use your computer for about 2 hours and then it will restart. Microsoft built a little time bomb into the beta to remind users to upgrade or remove the operating system. Subtle, not so much. Effective? Yes. Annoying? Definitely.

If you want to keep using a free version of Windows 7, it's time to upgrade to Windows 7 RC. But there's a time bomb on the release candidate as well. Starting on march 1st, 2010 it will begin restarting every two hours as well, and come June 1st, 2010 it'll just stop working. But since Microsoft will begin shipping the full version of Windows 7 on October 22nd of this year, you should have plenty of opportunity to upgrade by then.

In the meantime, Microsoft is essentially letting you run (and test) Windows 7 for a year and a half for free. Just remember to download Windows 7 RC by August 15th.