KVM

Create a image file:

$ qemu-img create -f qcow2 wheezy.img 50G

Install the system:

$ qemu-kvm -hda debian-wheezy.img -m 2048 -cdrom ../ISOs/debian-wheezy-DI-b4-amd64-netinst.iso -boot d -vga std

Boot the system:

$ qemu-kvm -hda debian-wheezy.img -m 2048 -vga std

Boot the system, without UI, with SSH port forwarding

$ qemu-kvm -hda wheezy.img -m 2048 -net nic -net user,hostfwd=tcp:127.0.0.1:2222-:22 -display none