p2v migration of a standalone server

https://www.experts-exchange.com/questions/24987102/Move-from-Physical-to-Virtual-Hyper-V.html

 Make a complete backup image.  Install Hyper-V.  Restore your backup as a new virtual machine.  Do not do this in a live environment...make sure it is well tested before you make the switch.  

or

                Was this comment helpful?                          Yes                  No                    mutahir:             You can Convert your Physical SBS 2008 BOX to Virtual

Disk2VHD
http://technet.microsoft.com/en-us/sysinternals/ee656415.aspx

Simply use the utility above to convert all the SBS partitions you have on your physical server to VHDs then create a Hyper-v VM and add the appropriate VHD's in the right order

That should get you started without changing the source server

Next is :

Take a full backup of your SBS 2008 on a external USB drive
restore it in a Virtual Machine on Hyper-V

http://blogs.technet.com/nking/archive/2008/12/17/bare-metal-restore-with-sbs-2008-running-virtualized.aspx

For restoring in a VM :

1 - Create a new VM in Hyper-V

You can use a tool called quick vhd to quickly create any fixed size vhd's
QuickVHD : http://code.msdn.microsoft.com/vhdtool
You can use bitcalc (google bitcalc) and then calculate the exact size in GB to make your quick virtual hard disks

2 - Insert your SBS Disc-1 or the map the SBS DISC-1 ISO in Hyper-v VM as the boot device
3 - Switch on the Virtual Machine and follow the link above from there on

HTH

I ended up backing up SBS with the built-in System Backup on an external drive, then rebuilt the server (with Server 2k8R2) and deployed Hyper-V, followed by restoring SBS during the creation of the virtual machine.
Worked like a charm. Thanks for the hint.

MG