Official Way to Install and Use Windows Vista

default, Windows Vista can be installed, used and run without any
license, product key or the need of activation for 30 days grace
period, for purpose of trial or evaluation. Although Microsoft
initially stressed that users should purchase a license with valid
product key before the trial period expires, or else Windows Vista
will lock into Reduced Functionality Mode. However, a "rearm" method
has long since been discovered to be able to extend, or reset the
remaining time for activation to another fresh 30 days, for up to 3
times.

Now Microsoft has confirmed that Windows Vista can be used and run for
120 days or 4 months (3 rearms), and extending the activation grace
period is not a violation of the Vista End User License Agreement
(EULA). All versions of Vista include Windows Vista Ultimate allow a
30-day free period without activation, except the corporate-oriented
Vista Enterprise, which supports only a three-day trial.

To extend, reset or restart the initial OOB grace period of Windows
Vista to another 30 days, use the following steps:

1. Click on Vista Start button and key in "Cmd" (without quotes) in
Start Search box.

1. Press on Ctrl-Shift-Enter to open Command Prompt with
administrative credentials (equivalent to "Run as Administrator").
2. In the Command Prompt, type the following command and press Enter when done:

slmgr -rearm

You can also use "sysprep /generalize" (without quotes).

4. After a few seconds, the confirmation dialog window will appear.

Reboot the computer.
Rearm again when the remaining activation grace period timer counts
down to 0 days.
Rearm option resets the computer's activation timer and reinitializes
some activation parameters.

Enjoy