Microsoft has issued a hotfix for SLI and Crossfire based graphics cards with two or more GPU's on the same card, such as the GeForce 7950 GX2, as until now, Vista has not recognised more than one GPU on these types of cards.
There are of course a couple of other cards that are affected such as the various limited editions from Asus, Gigabyte and a few others, but the GeForce 7950 GX2 is the most common dual GPU SLI card.
But with more cards on the way, especially dual Radeon HD 2600 XT based cards, this seems like an important thing to fix, or there will be many a unhappy gamer out there.
But the silly thing is that you can't just download this hotfix, you have to contact Microsoft support to get your hands on it and you might even be charged for the support call and the hotfix. Luckily Guru 3D has a mirror where you can download the hotfix from.
Although it was only posted last week, it seems like the hotfix was ready on the 31st of May and took over a month and a half before it even appeared on Microsofts site.
Wonder what else is broken in Vista...
More here and the Guru 3D mirror can be found here