Forget running the Windows 7 RC until October 22. If you can get your hands on the release-to-manufacturing version, you should be able to use it for up to four months without entering an activation key. ComputerWorld has confirmed this with Microsoft, which says the procedure is completely legal. Behold:
Microsoft confirmed that "-rearm" can be used as many as three times by Windows 7 users to avoid activation. "This means [that] a total of 120 days total time is available as a grace period to customers that take advantage of -rearm," said a company spokeswoman.
Nor is extending the grace period a violation of the Windows 7 End User License Agreement (EULA), the spokeswoman said.
As Windows Secrets explains, you can install Windows 7 without providing an activation key—just hit "next" when the installer prompts you. From that point on, Microsoft gives you 30 days to activate before flipping over to a reduced-functionality mode. However, you can reset the timer up to three times by simply opening a command prompt window, entering "slmgr -rearm" without the quotes, and rebooting.
Once the 120 days are up, you should be able to enter a legit Windows 7 key and keep using the same installation. There’s a catch, though. Windows Secrets notes that the RTM disc image installs Windows 7 Ultimate by default, and entering a key for a cheaper edition won’t work. However, if you use a utility like gBurner to delete a particular file (ei.cfg) within the ISO image, you’ll be able to select any edition you want during the installation process. Check out the Windows Secrets article for detailed instructions.