As a test I thought I would see how the SBS 2008 backup handles restoring to a Hyper-V virtual machine. The P2V was successfull but of course there are some issues to deal with.
This is how I did it on a Windows Server 2008 R2 standard machine.
1. Attach the USB backup disk to the Hyper-V host.
2. Open Computer Management -> Disk Management and take the backup disk offline. This allows Hyper-V to attach the usb disk as an internal IDE disk.
3. Open Hyper-V manager.
4. Edit the properties of your SBS 2008 VM. Set the usb disk as the secondary device on the primary IDE channel.
5. Boot the VM using your SBS 2008 DVD or ISO.
6. Restore the system using Windows Complete PC restore.
7. When the restore is complete the VM will reboot. If everything is OK you should eventually see the login prompt.
8. You will need to rerun the connect to internet wizard to fix the network. I also noticed you’ll need to reimport your SSL certificate, so make sure you have a backup of that handy!
That was as far as I got in testing but from what I could see there shouldn’t be a major problem doing a P2V of SBS 2008 to Hyper-V.