Reinstalling Windows 7 x64?

Hi!

I have a bit of a problem here. I installed Windows 7 Professional x64 from MSDNAA 2,5 years ago, and due to installing and uninstalling a lot of software, I think it's time to do some reinstallation.

But, here's the problem. I lost all my data related to the MSDNAA and system - lost MSDNAA password and my serial number (key) is on that site.

And, now, I'm trying to find MSDNAA version of my windows on internet. I found some installations, but now I have some questions.

1) Do I need my key for reinstalling Windows on the same computer (I think not, but not sure)?

2) If I do need it, is there some software that can dig up key from the system files, and can you give me a link?

3) I heard every MSDNAA Windows installations works only with the key supplied with it, so, if I download some MSDNAA Windows 7 professional x64 instalation, will my key work with it?