Can I run multiple copies of SQL Server at the same time on one computer?
A. No, except if you have an active/active failover configuration hosting separate SQL Server 7.0 virtual servers on a Microsoft Cluster Server (MSCS) and one of the nodes fails. Although you can use the SQL Server 7.0 Vswitch.exe utility to switch back and forth between a single copy of SQL Server 6.5 and a single copy of SQL Server 7.0 on one computer, only one version can be active at a time. This utility was not intended to allow both versions to be actively used on a server; it was intended to provide you with the ability to switch from one version to another when necessary.