Preparing for the big CES launch, Microsoft made available the new Windows Vista Business Edition on the Virtual Labs facility, powered by Virtual Server, where customers can connect and test several scenarios.
Each of 18 labs is available for 90 minutes and you can download a related manual. Try them here.
Microsoft has tents of other publicly accessible virtual machines, arranged in facilities dedicated to system engineers (TechNet Virtual Labs) and developers (MSDN Virtual Labs).