Quote Originally Posted by kaffenils
SQL Server 2000 must run as a service. With SQL Server 2005 you can access the database file directly in the connection string, but I don't know how performance, multiuser and functionality will be compared to running it as a service.
It still runs as a service when you open it in the connection string - SQLSERVER.EXE still runs and listens on it's ports as if the DB was permanently attached.

I've not fooled with it but I'm guessing you can several users connect to the DB even if they "connect/attach" in the connection string.