Now that the RTM of Vista  is in MSDN, I just had to try it out in VPC.  The good news is Vista just installs. No messing around. Put the CD, I mean DVD in, and click, next, next, finish:

8:00 AM Start Virtual PC 2007 Beta and create a Vista VM with 768 Meg Ram
8:01 AM Boot from DVD
8:03 AM Click next to regional settings
8:03 AM enter key
8:05 AM Select disk and ok
9:00 AM reboot
9:01 AM Regional settings
9:04 AM Checking performance
9:07 AM Preparing Desktop
9:15 AM Voilia, the Vista desktop
9:20 AM VMadditions install finished, reboot.

Installing the additions requires a few extra clicks now with UAP enabled.

Vista is reasonably smooth and snappy. Sound works nicely, animations fade in and out - but more importantly my dynamic screen size works as expected, and using RDP from my Vista Host to Vista Guest gives me Aero Glass  :)    

Currently my host is running 32 bit Vista - my next step is to try it all again with a 64 bit host.