A lot of the time I a recommending to IT Pros that they should go ahead and download a copy of Exchange 2007 in their 'spare time'.  Although this sounds like a great idea in principal,  I can imagine that not everyone wants to spend their evenings and weekend a) downloading Exchange 2007 and b) installing it into a virtual machine. 

Bearing that in mind,  I came across a post on Steve Claytons blog that links to pre-configured virtual machines for Exchange as well as Vista and Office.

Pop along here and download the Exchange 2007 VHD which includes Office Live Communication Server 2005 .... bargain!