Vista Activation time can be extended using the following trick, provided it has not been activated online:
Step 1:Browse through REGEDIT
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ CurrentVersion \ SL
Step 2: Right-click the Registry key named SkipRearm and click Edit.
The default is a Dword (a double word or 4 bytes) with a hex value of 00000000. Change this value to any positive integer, such as 00000001, save the change, and close the Registry Editor.
Step 3: Start a command prompt with administrative rights. The fastest way to do this is to click the Start button, enter cmd in the Search box, then press Ctrl+Shift+Enter. If you’re asked for a network username and password, provide the ones that log you into your domain. You may be asked to approve a User Account Control prompt and to provide an administrator password.
Step 4: Type any one of the following two commands and press Enter:
Either command uses Vista’s built-in Software Licensing Manager (SLMGR) to push the activation deadline out to 30 days after the command is run.
Changing SkipRearm from 0 to 1 allows SLMGR to do this an indefinite number of times. Running either command initializes the value of SkipRearm back to 0.
Step 5: Reboot the PC .
After you log in, if you like, you can open a command prompt and run the command
slmgr -xpr to see Vista’s new expiration date and time.
Hope this helps.