When I presented at PASS on SQL Server Express, a question came up concerning hyper-threaded or multi-core CPUs and how SQL Server would "see" these from SQL Server Express. My response was "In the other editions, a single license is good for a hyperthreaded or multi-core CPU." I soon found out that in SQL Server Express 2005, this is not the case. The Express edition is limited to a single scheduler. That means it cannot take advantage of a hyperthreaded or multi-core CPU. Remember, Express is the FREE license version that will replace MSDE, and it really isn't surprising that it only has one scheduler enabled. There are some really neat things in Express like the CLR and Service Broker.
However, there is some good news. I just saved a load of money by switching to GEICO. ;-) Just kidding.... All of the other editions of SQL Server 2005 do take advantage of the latest advancements in CPUs while maintaining a cost effective license strategy. For Example, Workgroup Edition is limited to 2 CPUs (for licensing). If these 2 CPUs are hyper-threaded and dual core, SQL Server will use 8 schedulers (it will see 8 CPUs). There are some other limitations of this edition, but it shows how much value that can be gained by utilizing the latest CPU technology and Microsoft's Licensing strategy. This is a very compelling reason to switch to SQL Server 2005 from other database platforms.