I must somewhat sheepishly admit that I'd never heard of Sun's VirtualBox virtualization solution, but a few people recommended it today on Twitter so I thought I'd give it a look. What I see looks promising. On Windows (client), there are two traditional virtualization solutions that most people are familiar with, Microsoft Virtual PC and VMWare Workstation. Virtual PC is free, which is a plus. But it's limited in some ways compared to VMWare WS, including such things as support for USB, and it doesn't perform as well. I use both, for whatever it's worth, but most of my VMs are in Virtual PC format.
Anyway... VirtualBox is also free. But like VMWare, it supports USB. It also natively supports a lot of Linux distributions which is yet another problem with Virtual PC. So it's worth looking at.
Here's what the VirtualBox site has to say about the product:
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software.
Presently, VirtualBox runs on Windows, Linux, Macintosh and OpenSolaris hosts and supports a large number of guest operating systems including but not limited to Windows (NT 4.0, 2000, XP, Server 2003, Vista), DOS/Windows 3.x, Linux (2.4 and 2.6), and OpenBSD.
VirtualBox is being actively developed with frequent releases and has an ever growing list of features, supported guest operating systems and platforms it runs on. VirtualBox is a community effort backed by a dedicated company: everyone is encouraged to contribute while Sun ensures the product always meets professional quality criteria.
I'm installing Ubuntu Linux under VirtualBox as I write this. If this works as advertised, it could be a compelling alternative.