Andy Governor Inc.

How to extend Windows 7 30 day Trial to 120 days:
Step 1: Click Start, All Programs, Accessories.
Right click command prompt and choose Run as Adminstrator.
Enter your adminstrator password.

Step 2: Type the following command prompts and press enter:
slmgr -rearm
note the space after slmgr and the hyphen in from of rearm.

 Restart Windows 7

You would notice the properties dialog describes you have grace period of 30 days
You can run this -rearm trick fo as much as 3 times.