There is an article on Slashdot about VMWare releasing a free "VM
Player" that lets you use VM images created with one of their other
products (Workstation, ESX, GSX) on any machine running the player. One
of the downloadable examples is a VM image providing basic communication
tools (Firefox, Thunderbird, Gaim, etc.) that effectively keeps those
services inside a sandbox.

The player is available at http://www.vmware.com/products/player/ but
the site is pretty slow this morning.

--rick