from http://www.sqlmag.com/Articles/Index.cfm?ArticleID=4889

Which version of Open Database Connectivity (ODBC) drivers do I need to talk to SQL Server 7.0?

All SQL Server 7.0 tools use either ODBC or Object Linking and Embedding Database (OLE DB) to access SQL Server except isql.exe, which still uses DBLib. Therefore, you must have up-to-date ODBC drivers to use SQL Server 7.0 tools, which use ODBC 3.70 drivers. These new drivers understand how to communicate with SQL Server 7.0, and fully support features such as Unicode. The drivers are fully backward compatible, so you can talk to earlier releases of SQL Server and SQL Server 7.0 with the ODBC 3.70 drivers. You cannot use the ODBC 2.x drivers successfully on the SQL Server 7.0 computer. On client computers, you can still use the older ODBC drivers, but you will lose some functionality such as sending and receiving Unicode datatypes. Also, Microsoft is not shipping any 16-bit ODBC drivers for SQL Server 7.0, but the SQL Server 6.5 drivers will still work.