First of all I would like to thanks Randika at Dept Physics , UOC for giving me this crack. Its a pretty nice trick. It can be used to postpone activation period of Windows 7.

May be you have noticed there is a evaluation period before activating the Win 7 OS automatically. If you check the properties of computer you can see the remaining days. To reset the evaluation period follow the given method.

Method:

1. Start command prompt as the administrator.
2. Type “slmgr -rearm”
3. Restart the machine

Now you have another 30 days.