The QuickTime 7.5 update appears to have broken sound in VMWare Fusion, and also in some code I’m working on. I will know more once I have fixed the issue in my own code. But for now, I advise waiting to update QuickTime to version 7.5.
UPDATE 2008-06-19: problems in my code solved. Basically I was specifying a bit-rate for a compressed audio stream, and QuickTime expected it to be 0. Earlier versions of QuickTime didn’t care, but 7.5 was more strict. Also, the VMWare problems have been fixed.