When Microsoft makes the already-leaked release candidate for Windows 7 available for everyone next Tuesday, May 5th, they're giving the software away for a year. Its expiration date is June 1, 2010, so you can play with the shiny, smooth, all-fixed, wonderful operating system from Microsoft for almost 13 months before you have to pony up. The real, shipping version will be available toward the end of this year (it could ship as early as October 23), but that pre-shipping test "release candidate" works so well, why buy the final version?
The stickier question is, how will all of us feel about paying for Windows 7 after using it free for more than a year? Studies show that it feels great to have something given to you for free, but it hurts a whole lot more (and it's a whole lot more memorable), when something is taken away from you. But then, Microsoft is probably willing to risk this conundrum, desperately wanting to shed the negative PR juju it built up with Vista.
If you've been testing out some of the various beta builds up until now, Microsoft recommends that you start from scratch with this release candidate, also known as build a 7100. However, if you don't feel like redoing everything on your PC, there is a workaround, and it's as easy as changing one number in one file, and then you can upgrade to the release candidate.
Don’t forget you can start downloading it tomorrow.