Virtual machines can be quite helpful reversing tools, and as they get more advanced, their usefulness and importance will increase even more I would guess (really looking forward to the new Unity mode in VMware 6.5, and what might follow from it!).

The VMware VIX API (http://www.vmware.com/support/developer/vix-api) is a nice interface to script VMware operations from other programs (the first baby steps towards ring -1, wee ).

Apridgen just released updated Python bindings for it too, if anyone would be interested in that:

https://www.openrce.org/blog/view/1124/PyVix,_Python_Bindings_for_the_VMWare_VIX_SDK

A word of warning before you upgrade to Workstation 6.0.3:

So, there is no way to launch a GUI program under Windows Vista at this time, unless you roll your installation back to Workstation 6.0.2.
We are working on a mechanism that will allow VIX clients to use the guest user's session, but I can't give a date for when this will be available.

http://communities.vmware.com/thread/142867?tstart=0