See also more Hyper-V pages
http://blogs.msdn.com/b/virtual_pc_guy/archive/2008/08/26/hyper-v-export-import-part-1.aspx
http://www.petri.co.il/importing-and-exporting-your-virtual-machines.htm
http://blogs.technet.com/b/heyscriptingguy/archive/2013/05/31/import-multiple-virtual-machines-with-windows-powershell.aspx