Sun's FOSS VirtualBox hits the sweet spot for Linux (ITWire)

The thing about Virtualbox is that it's user friendly. It has a nice user interface and is
generally pretty easy to do.

For example the non-free one supports USB 2.0. You can use the GUI to add and remove USB
devices on the fly. It supports automatically resizing the Windows desktop so that you can
resize the VM display like any other desktop application. 

For the fully-free crowd KVM is probably the closest, but it completely lacks any sort of easy
user interface. It's one of the things that they really need to work on.

Xen, in comparison, isn't even on the map. It's much to much of a PITA to lift your OS into a
hypervisor to get Xen working. It's totally unsuitable for the sort of work that Virtualbox is
good at.

Now for server work, that's different. 

Now I like KVM and I think that it can do it all. Were you don't have hardware to support KVM
then Kqemu is pretty darn close-enough. But I can't comfortably tell my friends to ever use
that software since I know they won't be able to get the sort of stuff they need working
working.