The machine is dual Xeon E5520, 10 GB RAM. The task is to run a Win32 middleware on a VM with snapshots and no display but RDP. At the same Firebird database, mail and OpenVPN servers are to be run natively. OS id Debian 5.0.5 x64. What free VM system is going to be the most efficient and easy to setup and manage? KVM, Quemu, VirtualBox, or something else?