I just setup a new SBS site. All windows 7 workstations were configured to use NT5DS (authoritative time). They were successfully syncing against the Windows Server 2008 SBS server.
Problem: Each time the workstations synced against the SBS server the time went back by 1 hour. You can force a sync using w32tm /resync.
This is because the SBS server is not syncing against an Atomic clock! Configure the SBS server to sync it's time against something (I use pool.ntp.org). Run the following commands on the SBS server!
w32tm /config /manualpeerlist:pool.ntp.org,0x8 /syncfromflags:MANUAL
net stop w32time
net start w32time
Then go to the Windows 7 workstations and run w32tm /resync. The time should be correct.
Note: Workstations will automatically sync.