Vista - Internet Streams Choppy

I have never seen an answer for this yet I have seen this on many Vista PCs.
Internet Radio/Video, regardless of source, bit rate or player (Windows
Media/Itunes/Real)is choppy with frequent, often very long pauses for
rebuffering.
XP boxes on the same networked DSL connection have no such problems, nor do
computers that dual boot into XP when booted to XP.
I have seen this on both DSL and Cable internet connections.
Clearly something is awry in the way Vista acquires or buffers these sources
compared to XP.
Not everything in Vista is worse than XP: Hearts and Solitaire are clearly
better in Vista.
Gotta go: the NPR stream just dropped out AGAIN!