Microsoft now has a collection of Virtual PC/Virtual Server VHD images to trial a decent range of their enterprise products. They currently have Windows Vista, Visual Studio 2005 Team Suite, Windows Server 2003 R2, SQL Server 2005, Exchange 2007, and several others. These should be really useful for testing their new products without requiring a spare machine and also for testing your own software against their various platforms. Hopefully they will continue to keep their images up to date and expand on the packages available.