Microsoft has been eagerly awaiting the first crop of true DX10 titles to be ready, and it stands to reason that once these amazingly gorgeous titles ship Vista will become the new standard OS for many gamers. Until then, MS has been busy making a few titles only work on Vista, such as Shadowrun.
But the question of whether or not this is intentionally crippled as a method to perhaps boost interest in Vista has probably been answered by a group of crackers calling themselves Razor 1911:
"Microsoft has been displaying a rather schizophrenic attitude towards PC gaming recently—on one hand, the company wants the PC platform to be recognized as a first-class gaming citizen, but at the same time it is fragmenting the market unnecessarily with the release of Vista-only titles such as Halo 2. Now, the cracking group Razor 1911 has fought back against the idea of Vista-only titles, with the release of a patch for Microsoft's new game Shadowrun that allows it to be run on Windows XP."
Microsoft might just have to play the waiting game while developers continue to work on true DX10 masterpieces. Interest in Vista could very well pick up once there are enough quality titles on shelves that truly require DX10.