Hell, it's about time that someone compromised the foul exclusivity of the so-called Windows Vista games - namely Halo 2 and Shadowrun, so far. In a classic example of
"bringing the mountain (DX10) to Mohamed (XP)", some 'warez' groups eventually managed to crack both games, in order to make them run on Windows XP. Something that was officially impossible, if we were to trust Microsoft's word.
Even though the way this was done is not exactly noble, the same thing goes for Microsoft's practices too. And if there was still any doubt about it, we're now convinced that they shamelessly lied to our face, hoping to shove their new Vista operating system down our throat.
Of course, we can't recommend you to experiment will all sorts of dubious cracks, because the issue of software (in)compatibility between Vista (actually DirectX 10) and Windows XP should soon be solved in a more elegant - and more general way, not just for Halo 2 and Shadowrun. Among the ones currently taking care of this are Falling Leaf Systems, who last month officially announced their intention to launch a software package that would also allow running the two games on XP:
"First [Microsoft] claim that it was impossible to implement DirectX 10 compatibility atop Windows XP, and now they also want us to believe that they couldn't successfully launch two DirectX 9 based titles on XP either. We plan to expose both theories as patently false."
Unfortunately for them, the pirates came through first.
(N.B. Archive text, links removed)