This is probably close to the mark. Here are some new features for Vista:
The Multimedia Class Scheduler Service: basically a service that juggles thread priorities keeping "important" ones (read: audio playback) near the top:
The I/O system in Vista also has an idea of different priority packets. Therefore the disk read for the next MP3 frame is probably a higher priority than the read for the next network packet.
So what do I mean? I believe two unintended consequences of the rise of the media and leisure activities are overestimation of risks and lower risk tolerance.