In distributed installations, you can use only Microsoft SQL Server 2000 as the database. When you're performing a standalone installation, the deciding factor for whether to use SQL Server or Microsoft SQL Server 2000 Desktop Engine (MSDE) is knowing how many simultaneous users you plan to support. MSDE's managed concurrency workload governor lets it support only five concurrent workloads at typical speed; all subsequent connections run at a significantly degraded speed. Therefore, I recommend using SQL Server 2000 for the Universal Description, Discovery, and Integration (UDDI) database. SQL Server 2000 must already be installed on the same machine as UDDI Services, or you must be able to point to an existing instance of SQL Server 2000 on another machine before you can install UDDI Services.