ODBC to MSSQL - how?

Hello,
I am running an app with InstantRails v1.6 on Windows Server 2003 (IIS6
is turned off, I'm running on Apache w/ MySQL), and I have an ODBC
connection setup with "administrative tools > data sources (ODBC)" to an
MSSQL db on another machine. How can I connect to that in addition to
the MySQL db from my RoR app? I only want to read from that DB, no
writing involved. I haven't used ODBC before, so any help is
appreciated!

Thanks,
- Jeff