I just now got around to trying my Sansa with Rhapsody in Windows 7 and it does not work. The same client would work in Vista (as long as you ran it as Administrator) but it will not work in 7.
The client itself will work correctly, but when you connect the Sansa to the USB connection Rhapsody will never see it. I tried to add a device in preferences but it locks up the client.
I’ve just found out that Rhapsody is working on a new version (due out in the first half of 2009) so maybe all of these problems in Vista/2008/7 will all be fixed! 🙂