My Audigy4 was messing up when I first installed W7, so I went to Soundblasters website and downloaded the latest Vista drivers. It helped the problem, but it also means that I could not install the CD apps. The latest drivers are not compatible with those apps. The description also said that the Creative mixer would be installed with the new drivers, but I have not found it.
i too have an audigy 2zs with 5.1 speakers. i cannot get 5.1 sound to work. at best, was getting 4 speakers to work. i was able to get cmss, but not cmss3d. i just purchased an optical cable so hopefully that will get my 5.1 sound back.