I think Microsoft should do two things:
1. Push Windows 7 as superior. In my experience and that of others who have used it, so far it really is. (NB: The people that have used it were not die-hard fans either way, so naturally there will be Mac fans who disagree but this isn't the point).
2. Offer a Mac-Only version of Windows at a cheaper price to get more windows installs on mac (price of Windows OS for someone using it as a second OS is quite prohibitive).