From 1 January 2009, Visual Studio Professional licence only customers can add an MSDN subscription and save hundreds of $$$.  An MSDN Premium subscription offers access to almost all of Microsoft's server products and Windows operating systems, a full production license of Office 2007, Expression Web 2 and Expression Blend 2, heaps of technical support and resources, and upgrade rights to the next version of Visual Studio (due for release later this year).  Check out the details of this and other Visual Studio offers here...