win 7 & mobo

I installed Windows 7 Home Premium (32-bit) on my computer soon after it came out, having built the rig myself, so it can't be an OEM. On the box it says "for use on one computer," and the box contained two DVDs for the different "bits," (i.e. 32 and 64), together with the liscence keys.

While I realize that I can reinstall it on this computer should it ever be necessary I do have a question.

If I need to replace the mobo, or even build another rig, can I install the OS on the new mobo, or new rig? And can I use the 64-bit version instead?

OR, will I have to buy Win 7 all over again?

Currently, what I bought is the full retail version. It came in a plastic box with 2 separate DVDs, one for each bit size. But it only had one liscence key - to be used for either version

Thanks, and sorry if I've posted in the wrong section.

Thanks for the info.

Something may have gone wrong here as I had another answer but can't find any way to make it show up in this thread. It was from gregrocker and said:

Is it OEM version or not as you don't make it clear?

If so changing the mobo is supposed to prohibit reactivatiion, however there are numerous reports that MS phone activation is making exceptions for replaced mobo's. But you cannot count on this.
One workaround used by tech support is to replace exact mobo.
You would want to either clean reinstall or SysPrep the HD on the old hardware first to remove all drivers so it will start on the new hardware. SysPrep to move HD to another computer (Windows 7 Installation - Transfer to a New Computer) .

To which I can reply no, i'ts not OEM, sorry for not making that clear. And as for trying phone activation I can't do that as it's too expensive to call MS from the UK. Neither can I replace the exact mobo as it's no longer available from Ebuyer, where I shop, and in fact I don't need one at the moment. It was really just a question for future reference when I build my next rig.

Thanks for the link, a very interesting read which I'll make a note of.

Very many thanks, indeed, gregrocker. That really does answer my question.

And, as for activation by phone costing from the UK, I'm afraid that was something I just assumed. So the link you gave was very helpful. I had no idea that was how it worked.