Been running Vista 64-bit for months now. Only recently got the board, but runs like clockwork.
Have just changed from an Ati 1900 card to an 8800. Getting odd bits and pieces happening, but from all the reading I have done, it's got nothing to do with the board and everything to do with the card.
Dual-boot is definitely an option... I', actually thinking of running XP-Pro 32-bit for all the stuff that there ain't drivers for yet, and keeping my Vista 64-bit for normal use.
BTW... I have not been disappointed in the overclocking arena, if you do decide to stretch the legs a little.