Maximum PC

So I'm getting ready to install my $15 upgrade from Win7 to Win8 (the promo I got when I purchased my current laptop about 3 months ago).
Anyway, I have a clean image of the entire hard disk after a fresh install of Windows 7 and all the drivers, etc.

I am going to back up my data, and restore that fresh image onto the drive, and then upgrade to Windows 8. After the upgrade, I'm going to re-image the drive with Windows 8 installed, but want to go back to using my Windows 7 install (the reason I'm doing this is so that I can still get Windows Media Center for free before the January cut-off date and so I can get my Win8 upgrade installed before they change anything). But, we are not yet Windows 8-ready at work, hence the fact I have to then restore the Windows 7 image back onto my laptop. I just want to do this also so that I can move to Windows 8 quickly (since I have spare time now, and probably won't after the new year).

So, my question is, that once I do the upgrade to Windows 8, will that make my Windows 7 license/activation invalid, in that it will declare my copy of Windows 7 (which came installed on my laptop) invalid and no longer genuine (and thus, not be able to get any Windows 7 updates)?

I'm about to do this, but if this procedure will cause an issue with me restoring my Windows 7 install after doing the Windows 8 upgrade and image, then I'll just skip out on the $15 upgrade and use my retail upgrade (which I got for $70, which was to be used for another computer but I could use it on the laptop if needed).

???

No, as long as you uninstall the Windows 8 on top of it.