Don't know if it's *better* but it is open source. They do have a 'commercial, but free-to-use' one with USB support, and remote-desktop built-in.
I find it works really well, and run both Linux and Windows inside it with Ubuntu as the main host system. At the demo, we installed Ubuntu 9.04 into a Windows Vista laptop.
Really easy since you can mount your physical DVD drive from within the virtual system (so it takes control of it, in effect) -- through the click of a button.