To switch from SQL Server 7.0 to SQL Server 6.x
The -SwitchTo <60|65|70> argument determines which version of Microsoft® SQL Server™ to activate. The -Silent <0|1> argument determines if any user interface or messages are displayed. If 1, no user interface or messages are displayed. The default is 0.
c:\mssql7\binn\vswitch -SwitchTo 65 -Silent 1