At work we have a Core 2 demo running Windows Vista. This demo is not connected to the network because we don’t want people coming in and changing the background image to display something obscene or pornographic. There is a neat little trick that I found one day while trying to figure out how I could reset the time until the user had to activate Windows Vista.
What to Do
When you log into Windows and your grace period has expired, you can still use Windows with reduced functionality. In reduced functionality mode, you are still able to use IE7. This is where Microsoft dropped the ball.
Once the dialog box is open, you can then browse to the C:\Windows\System32\ directory. In the file name field, type *.exe and look for cmd.
The system will tell you that it successfully executed the program. Now you can reboot your machine and log on with another 30 days to activate Windows.