The Windows Vista Product Guide is available up on ms.com.  It seems to have finished its’ appearing-disappearing act and is up there permanently.  Some links strangely point directly to the word doc forcing you to download a 60MB file instead of the smaller xps version.  Here is the link to the page where you can make the choice between the two versions.

The doc is actually a great read about all the stuff in Windows Vista.  A good chapter on XPS is in there.

- Andy