In my opinion, you ALWAYS need to reinstall if you change a MB...
I know people will say they have done this and got away with it BUT, there is ALWAYS going to be little gliches and problems if you do this...
Its just software, if you try and fool it and switch critical parts around, you WILL have problems..
Just save all those headaches and REinstall, it will only take a few hours, TOPS, and then you will have a good, sound BASE to start from, one you can trust to be fairly stable and secure, (as secure as MS can make it) .
All of these workarounds are just that, flimsy patchwork, full of glitches, just reinstall and be HAPPY...
Just my 1 cnets worth..
SeeYa