or
You can use "DISK2VHD" as it will convert your DNS,DHCP,Print,Accounting server while it is online into a VHD, which you can then fire up in a VM and start testing / converting via SCVMM if you want to.
but if it is just ONE Server or even two or three, I would use Disk2VHD to convert it to a vhd
connect a USB Disk (suitable size for conversion) and then save the VHD over there.
http://technet.microsoft.com/en-us/sysinternals/ee656415.aspx