I'm deeply regretting backing the wrong horse by going with an AMD rig, and I would very much like to rectify the mistake by selling off my mobo and CPU and going for a... shall we say, a River Crossing that wouldn't go amiss at a Beach.
About the only thing holding me back is the fact that I need to figure out how to install my OEM copy of Windows 7 on the new mobo, or rather get it to work. Since it would be on the HDD, would I basically install the new mobo, Windows 7 would still work, but then I would need to re-register it?
I know that it's technically not allowed to reuse an OEM version of Windows 7, so don't go off about that.
You won't be able to reactivate Windows without calling Microsft. And I doubt they'll play ball with such a big change in hardware. Factor the cost of a new OS in; and if you're likely to upgrade again, don't go for an OEM version this time. For your requirements it's a false economy.
first is this a generic oEM version or is it a "dell", or other branded OEM Version
If generic OEM then you would have to delete from old system, or pull old HDD and put in new system (still requires a re-install., from there it's a 50/50 on whether you have to call uSoft. Although not totally ethical, they may be in a good mood. If you are "pitching" the old system - it died verses being unhappy. If you are selling your old system, then yes you should by a new copy.