Starting the April 2008 Edition of SSP, all primary is performed on Windows Vista SP 1 and full technical support is available for use with SSP on this platform. 

There are a few known issues that are documented, and it's possible that other issues may become apparent as more users migrate to Vista. The known issues with SSP on Vista include DVD compatibility, use of the QuickMessage utility, use of various third-party software products, and scenarios where earlier editions of SSP have been installed on Vista. Updated information will be provided in the Knowledge Base and the Vista Support forum as it becomes available.

However, if you are currently using Windows XP, there is no compelling reason, from a presentation features perspective, to upgrade to Vista at this time.