For all those who run Vista using Boot Camp, AnandTech says unfortunately you won't see quite the same 8.13 hours of usage.
Under OS X, this test yielded a battery life of 8.13 hours. The same test under 64-bit Windows Vista? Just over 6 hours: Thats nearly a 26% drop in battery life from OS X to Vista. When I first published these tests I spoke to a few PC OEMs to see if they had noticed any similar results. No one was willing to go on record but some OEMs did at least admit to seeing a ~20% difference between battery life in OS X and Vista.