I went from an Intel DG965RY with C2D E6600 and 2+2G of DDR2 667 MHz to a Gigabyte EP45-UD3R with C2Q 9550 and 2+2+2+2 GB DDR2 800 MHz.
Windows7 booted right up like nothing had happened at all, installed all drivers automatically, and was running perfectly within about 10-15 minutes.
I have posted this experience in an earlier thread, asking whether I should go ahead and do a fresh install anyway.
With Vista, I would have been looking at a repair install, bare minimum.
Most anticlimactic, as I, like kodi, was hoping to get away from a whole evening's worth of shopping with the wife.