Over the past few days, the news was flowing about the serious issues regarding an exploit in which Windows Vista which unknowingly gives the ability for a user to extend their activation grace period to indefinite time. To simply say for more than a year. The hack requires no special software or crack from a warez site but a simply registry can do it. This simple hack can disable the countdown timer for time left for activation.
Although your OS seem to be in trial mode, but yet you can enjoy the full functionality without even activating. KEZnews has posted a step by step tutorial for permanentely activating Windows Vista by patching timerstop system in windows.
Also another registry tweak available to extend the time period of windows activation by a small registry modifications.

PS: This post is posted not to promote the trick of exploiting windows in non-legal way but to help the public realize and make Microsoft Recognize about the issues.