I had the same problem; not having windows 7. I used ORCA (microsoft msi editor) to edit the installer, to remove the check for windows 7(table: launchcondition; edit 'Installed OR (VersionNT >= 601)' to 'Installed OR (VersionNT >= 400)' ), and the SDK happily
installed. Also all drivers seem to register correct, and the camera seems to work. Only the audio seems to need some extra work.
the microphone also seems to work, only the shapegame is complaining that some prerequisites are not installed. I can use the kinect as a normal mirophone. Would love to know if this will also work on XP..