HBO5
I also teach at the local community college. Here nstructors must hold a Masters degree.
As far as which track to concentrate on, what version of Office are you currently using? If you are familiar with one in particular I would go with that one. However, another consideration is the testing center. In my experience not all testing centers offer tests in all versions. Some are only capable of giving tests for XP, some only for 2000, etc.
If you are familiar with all versions, and can find a testing center that can offer tests for 2003, why not go with the latest and greatest.