Forcing Screen Resolution

I know that someone else has to have had this same problem, but I've
been unable to find a discussion that's both on point and with a solution.

A new 20" LCD (Westinghouse L2045NV) has been purchased that has a
native resolution of 1400x1050. There is no monitor "driver" available
for that particular model, as far as I can tell.

There is no 1400x1050 option for "Screen Resolution" even though the
graphics card (Radeon 9200) should have plenty of memory to accomplish
it. I see no way in the (current) version of Catalyst to force a
specific resolution.

How can I get the system to drive the monitor at its native resolution?