"recovering" Win7, after replacing original mobo

My failed original HP mobo was an Asus, for which I had Vista system recovery discs. I used the Vista discs as a 'base' from which to install a Win7 upgrade just a month or so before the mobo died.

Now, my replacement board happens to be an Intel, and I am using my original CPU. Boot-up is fine and was relatively easy (to my surprise, since this is my first such project). But I hadn't foreseen problems with reloading Win7.

Sure enough, the Win7 upgrade discs don't work alone to get me back to that OS, and I guess this is because they're looking for an existing Vista installation as the 'base' (keeps telling me the product ID number is invalid). So of course next, I tried starting with the Vista recovery discs - but those apparently also get rejected, and I suspect that's simply because they're looking for a machine ID from the original HP/Asus, and not my new Intel mobo.

So what's my least-painful, lowest-cost way back to having Win7 again? Is there an easy workaround? Need I buy a new Vista package to upgrade from, just because my old mobo failed? Is there a chance to beg MS to give me some kind of waiver/product code to use to bypass the old Vista installation, considering that I'd already 'paid' for Vista through my original purchase and Win7 via a more recent purchase, and it's just the hardware failure that now leaves me stranded?

And wouldn't Intel normally provide at least some form of usable OS with the replacement mobo package, even it it happened not to be one that I wanted?