So our MSAV folks have been working really hard this year to come on-line and our external virus encyclopedia is finally starting to kick ass!

Here's a link to our write-up of the Skype worm you may have read about recently:
http://www.microsoft.com/security/portal/Entry.aspx?ThreatId=-2147371021

Hmm - looks like it requires all sorts of admin privs to write to the registry and system32 etc.  On Vista with UAC enabled these write operations would just fail with an access denied since by default users don't run processes with admin privs on Vista with UAC.