First, I couldn't make a connection to my MS SQL database (2008), so I made a custom string and used a DSN. That worked fine (though I would like to be able to connect without a custom string).
Once that was done, I go to add a datasource, and it sees the data fine. However, I get this error when trying to test or save.

Hello Joe,

Can you please describe a little more detailed what do you mean by:

Quote

I couldn't make a connection to my MS SQL database (2008),

Are there any error messages? Are your Connection details right (server/port/username/database/password)?
There is absolutely no need of using custom string to connect to a mssql database with the DMXzone Database Connector.

The issue was solved in a Live Chat Session.
Joe does not have the SQL Server Native Client for SQL Server 2008, which contains the SQL OLE DB provider and SQL ODBC driver in one native dynamic link library (DLL) supporting applications using native-code APIs (ODBC, OLE DB and ADO) to Microsoft SQL Server.
The resolution is either to install the SQL Server 2008 drivers or to choose SQL 2000 as a server version.