Free Libre Open Source GPL

LinuxVserver∞
XenVirtualMachineMonitor∞
OpenVZ (by SWsoft)∞

Un-Open Proprietary

Parallels∞
SWsoft∞
VMware∞ Player (free-of-charge), Server (free-of-charge) , Workstation

Physical to Virtual (P2V)

During the transition phase you may want to P2V your existing non-osde desktop in to a VM on your osde
NortonGhost is a great tool to help you do this

Virtual to Physical (V2P)

This is where you create virtual template master builds then put (NortonGhost) then on to physical hardware