Ok fellows this is something I have read but not tried.. So at your own risk..
"Vista activation can be bypassed"
Windows Vista can be run for at least a year without being activated, according to Windows expert Brian Livingston. A single change to Vista's registry lets users put off the operating system's product activation requirement by an additional eight times, according to Livingston, who publishes the Windows Secret newsletter. This is five times over the three disclosed last month by him. In an article, Livingston had revealed earlier that a one-line command lets users postpone Vista activation by up to three times. Since Vista comes with initial 30-day grace period. An extension of additional three times means that users could run Vista for as long as 120 days before they are required to activate the OS. According to him, the one-line command can enable even novices postpone the product's activation deadline. In fact, Livingston said, with more research it may even be possible to find a way to postpone activation indefinitely. Though Microsoft had seemingly stayed unconcerned by Livingston's last month disclosure and flatly stated that using it would not violate the Vista End User License Agreement (EULA), this time the company has labeled the registry change as a "hack." However, Livingston refutes the "hack" charge, saying, "This isn't a hacker exploit. It doesn't require any tools or utilities whatsoever." He also cites that Microsoft has even documented the Registry key, although obtusely, on its Technet site.
Here's a step-by-step guide into Livingston's finding:
Step 1: While running a copy of Windows Vista that hasn't yet been activated, click the Start button, type regedit into the Search box, then press Enter to launch the Registry Editor.
Step 2: Explore down to the following Registry key: ......
