lonesometrainer writes: "Innotek's virtualization solution VirtualBox is available in a free/opensource and a commercial variant. Unlike XEN or KVM (Paravirtualiziers) and more like VMWare it emulates the hardware available in the VMs (by making use of Qemu). Innotek is no newbie in the virtualization market as they developed the VirtualPC solution together with Connectix. German magazine Heise seems to be pretty satisfied with the product overall (original article in german, google translation). Host systems may be Windows 2000, XP, 2003 Server or 32-bit Linux systems (Innotek is currently working on support for Mac OSX and 64-bit Linux). A wide range of guest systems is supported."