The same Shadowrun that was developed exclusively for Windows Vista, apparently doesn't need Vista or DirectX 10. A lot of people are still stuck with XP and DirectX 9, and from my point of view this is a good thing.
All you have to do is replace some of the files in the installation folder with new ones from Razor, and you shouldn't have any problems running it under XP. Of course with this crack you will not be able to play the game online, so you're left with bot's and LAN.
Microsoft should be happy with this, since a lot of people will probably buy the game to run it on their XP systems. There are some rumors about a patch that makes Microsoft Vista exclusive Halo 2 work under XP. Nevertheless, Falling Leaf Systems is working on a software library that will allow Halo 2 to be played under XP, and it should be ready by the end of July.