If you have SQL based apps, they will have to upgrade to SQL 2005 SP2 (that includes the MSDE replacement SQL Express). e-Week noted ( SQL Server 2005 SP1 Users Face Vista, Longhorn Glitches ): These two operating systems will only support SQL Server 2005 SP2 "or later when it becomes available," according to Microsoft's SQL Server support Web pages. But there is no indication on these sites of how soon it will deliver SP2 or whether it will deliver the service pack at about the same time Vista and Longhorn are released. the CTP of SP2 is available at http://www.microsoft.com/sql/ctp.mspx More information on the problems users experience when not running SP2 is available at http://www.microsoft.com/sql/howtobuy/sqlonvista.mspx with support information at http://www.microsoft.com/sql/howtobuy/windowsvistasupport.mspx which notes: Known Issues This section describes known issues that relate to installing and running SQL Server 2005 on Windows Vista and Windows Server "Longhorn." Issues Related to User Account Control...