Microsoft® SQL Server™ 2000 can be installed on the same computer with Microsoft SQL Server version 6.5, but only one version can be active at one time.
Note Switching between versions is not the same as running multiple instances. For more information, see Working with Instances and Versions of SQL Server.
After the SQL Server Upgrade Wizard finishes the conversion from SQL Server version 6.5, SQL Server 2000 is the active version of SQL Server. If enough disk space exists on your computer, you can keep the SQL Server 6.5 installation intact.
To switch from one version to the other, use the Microsoft SQL Server-Switch application on the Start menu, or run Vswitch.exe.
Important Be sure the SQL Server Upgrade Wizard is finished with its upgrade tasks, before you attempt to switch between the active and nonactive versions of SQL Server.
To switch from SQL Server 6.5 to SQL Server 2000