Whatt is the best way to create a virtual machine from UT9

I would like to create a virtual machine from my existing 9.4 Untangle. Then replace the hard drive and install 10 to the new drive. That way if I can't finish for some reason I can just swap the drive back.

It can be virtualbox or qemu. Just not sure if it would get to messed up to see the settings. Or the best way to create the image. The hardware is intel atom d525 with intel nics.

Thanks