The primary TDS version supported is 7.2. This means that Tedious should work with SQL Server 2005 and later. The integration tests pass with SQL Server 2005 and SQL Server 2008.
Some limited support has been added for TDS 7.1, for use with SQL Server 2000.
Later versions of TDS may be supported in the future, but it is unlikely that earlier versions will be supported.
The name Tedious is simply derived from a fast, slightly garbled, pronunciation of the letters T, D and S.