We just released two update packages which improve the performance and compatibility of Vista.  As far as I can tell, they aren't on Windows Update yet so you'll have to go get them manually.  The most significant in my mind is improvement for file copies from the Vista shell.  Anyone who has tried to copy even a small amount of data in Vista knows how painfully slow it can be.  These updates are reported to fix that.  I'm installing them now.  Here is Ars Technica's writeup on them.

The performance update is here.

The compatibility update is here.