I came across an article from Windows Secrets that shared a couple of tricks I think will be useful to small and medium-sized businesses currently evaluating Microsoft's new Windows 7 operating system.
Extend trial period up to 120 days
The first of the two tips involves extending the length of the default 30-day trial period up to 120 days. This is not about piracy, though, since activating - and purchasing - Windows 7 will still be required if you try to use it beyond 120 days. However, being able to use Windows 7 for so long has practical effects, especially for SMBs doing an exhaustive evaluation of the final release version Windows 7, but loathe reinstalling it every month.
To extend the trial, basically wait until the initial installation is approaching the end of the default 30-day trial before firing up a Command Prompt window with Administrator rights.
Type in "slmgr -rearm" without the double quotes at the command prompt, and restart Windows. Voila, you will now see the trial period reset back to 30 days; this trick can be repeated another two times to reach 120 days of trial in total.
Install any version from a Windows 7 Ultimate media
To be clear, there is no way to switch the edition of Windows once it is installed. What is possible, though, is to get a DVD with Windows 7 Ultimate, yet be able to install any version of Windows using it. This can be useful to reduce the amount of installation media that needs to be kept.
Anyway, the above-mentioned capability can be quickly unlocked by deleting a file named ei.cfg from the root directory of the DVD. Obviously, you will not be able to delete the file off a physical DVD itself. It isn't that difficult to create an ISO file from the DVD, though, or just download the ISO directly from Microsoft. Once the ei.cfg file is deleted, running the installation will result in the Windows 7 installer displaying all the versions of Windows 7 names for selection.
For more specific technical instructions on the above points, check out the Windows Secrets blog here.
In the meantime, you might want to check out the Windows 7 cheat sheet that I recently put together.