Hi markjoseph,
the L293 can not only drive DC motors, but also unipolar stepper motors. Therefor it has four inputs. To drive a normal DC motor two inputs are good enough to have to motor rotate in either direction and also brake regardless of the rotation direction. (So only 1/2 of the IC is actually used)
Google for it to obtain the data sheet.
The L293 is no "exotic" part. So you should find it at any electronics shop with a medium assortment of ICs.
I made the schematic using ISIS out of PROTEUS.
Boncuk