I have installed a new motherboard and hard drive, now windows 7 will not activate. any help will be appreciated. thanks.

If your original copy of W7 was OEM, then I think you will find it is tied to the "original" machine. Which means you would have to buy another copy to run on your new build. If on the other hand you had a full retail version of W7 then you should be ok transfering the license across to the new build.

solved. I have the retail version, the answer is activate by phone. no prob. thanks.