This article from Techworld.com seems to expand on the problems this will cause for some rather important medical apps:
"Vista has another playback quality reduction measure. It requires that 'any interface that provides high-quality output degrade the signal quality that passes through it if premium content is present. This is done through a "constrictor" that downgrades the signal to a much lower-quality one, then up-scales it again back to the original spec, but with a significant loss in quality.' If this happens with a medical imaging application then artifacts introduced by the constrictor can 'cause mis-diagnoses and in extreme cases even become life-threatening."
tinyurl.com/y3cug6
Edie