Windows 7: Product keys interchangeable?

I recently bought Windows 7 Professional via the student deal. I've read that when buying Windows 7 for the full price you get both the 32 bit and 64 bit versions included on the disc. This is not the case with the student deal as my cd includes the 32 bit version only.
At the moment I want to have the 32 bit version on 2 machines. But in the near future I want to have 32 bit on 1 machine and 64 bit on another machine.
If I also buy the 64 bit version, will I be able to use the product keys interchangeably? i.e. Can I install the 32 bit version from disc 1 but use the product key from the 64 bit disc 2?

Thanks in advance for any input.

Welcome to Seven Forums.

You can use the product key for either 32bit or 64bit, but can only use the key for one installation on one computer.

If you install Windows 7 Professional 32bit and use your product key to activate, then later you can install the Windows 7 Professional 64bit version and use the same key. Just not both at the same time.

Tongs, I am not sure I understand. You will, in the end, have a 32bit student version with one key and a retail version (32 and 64) with another key. You should use one for each computer / install.