REDMOND, Wash. — The window is closing on a free trial of Windows 7.

The code for the release candidate download of the new Microsoft OS is available until Aug. 15. After that date it can still be installed, but the code won't be available, reports CNET.

Another deadline is also in effect for those using a beta version of the OS rather than the release candidate. With a cutoff of July 1, the beta software still shut down every hour. The only way to remedy the recurring shutdown is to switch to the release candidate as soon as possible. The beta version expires completely on Aug. 1.

Microsoft adds that the release candidate also has a limited use life and will expire June 1, 2010, and bihourly shutdown will begin March 1 next year. Also, a switch from the release candidate to the final version of Windows 7 must be a clean installation.

Download the Window 7 release candidate here.