Right-click the WINDOWS desktop, choose New->Microsoft Data Link. That will bring up a dialog that allows you to configure and test your database connection. You might connect to the Access database via ODBC or directly via Jet Engine. The Jet Enginge saves you the trouble of creating an ODBC connection on your PC. After you leave the dialog, the "data link" will show up on your desktop as text file. Open it and copy-paste the connection string to your VI.
This webpage is an excellent resource for connection strings: http://www.able-consulting.com/ADO_Conn.htm
If your application requires users to change the database connection at runtime, you can also include the dialog via ActiveX (MSDASC.IDataSourceLocator).
