Windows 7 - can you install windows 7 on multiple machines

i bought windows 7 for my laptop and my mom has a dektop running windows vista i wanna know is it possible for me to use my windows seven disk on more than one computer useing the activation code and everything when it asks for my activation code will it not let me install windows 7 on her computer because i have already used the activation code when i installed it on my personal laptop pc. Thanks

I like short answers.

Nope, activation codes only work on one Machine at a time (if Seven came with a PC it can only be installed on that PC) and installing it on another machine would be illegal and against the EULA anyway.

Oli

With the rettail full install version of 7 Ultimate here being installed on a new build a call in to the automated operator was needed to see the fresh clean activated. When simply mentioning a hardware change without specifying the automated voice came back with: "I can see that was a change."! Automated voice?

With a swap out of one pair of dimms since then for a new pair that will now need another call due to the small hardware change seen with that as well. Other then volume licensing that clearly shows one license per one machine only and they can tell!

1 key and 1 install.