I just got a request for Symantec Antivirus for Windows Vista.  As luck 
would have it, I just downloaded the BETA Symantec AV Vista client.  It 
seems to install without issue on my 5536 build... I have not tried it 
on Beta 2 or 5472.  You can get it here:
https://www.uvm.edu/software/distribution/windows/antivirus/SAV_Corporate_Edition_10.0.1.628_WinVista32_EN.zip

If that URL gives you grief, you could try to access the same directory 
using CIFS/SAMBA:
\\zoofiles\software\distribution\windows\antivirus
then grab the file:
SAV_Corporate_Edition_10.0.1.628_WinVista32_EN.zip

FYI, I have added a community-editable page on the Vista "Road to 
Production"
http://sharepoint.uvm.edu/sites/ad/Lists/Vista/AllItems.aspx
If you have been doing any Vista application testing and want to add to 
or edit entires on this page, please dive right in and share your 
experience.

-Greg Mackinnon
CIT Technical Support Group

-Greg