One of the major problems with Vista was that you needed a graphics card. And to open your case and fit it. (Not that hard.) This being an extra expense on top of the cost of the O/S.
(I also got an extra 1 GB Ram and a 2 GB USB stick Readyboost - not that any USB stick was cert. for Vista.)
That's a lot of extra cost and handy person work for the average consumer ...
What will the situation be with Windows 7? OEM's will use all-in-one MOB's because it's the cheapest option. If selling system for $800, adding even a $50 card will loose you business to the other guy down the road.
Do you think motherboards with chipsets like AMD's 780G with onboard HD video support, ( + I believe, cross-fire support from an add in card AND the on-board graphics if upgrading) is the way to go???
What have Intel got?