Adrian,
Please be aware that the odbc-rails adapter doesn't currently support MS Access. The adapter isn't completely generic in that the adapter requires some database-specific information which ODBC cannot provide. Consequently, the adapter contains specific entries for each database currently supported. However, it's straightforward to modify the adapter to support a new database for which an ODBC driver exists. Alternatively, you could export your Access tables to one of the supported databases.
If you were to do this, your database.yml file should contain something similar to:
development: adapter: odbc dsn: local_odbc_name username: rails_dev password: rails_dev emulate_booleans: true trace: false
i.e. dsn refers to a Data Source Name configured with your ODBC Administrator.
Regards Carl Blakeley