Should IT know it all?

I have built or rebuilt all the PC’s for my company at one time or another with the operating system and software packages. There have been many times when employees have asked me questions about how to use these software packages. I’m somewhat familiar with MS Excel and Word although what I know is self taught and not nearly complete with all the uses of these programs. I usually tell them I don’t know if I don’t and than I attempt to find an answer for them. I have been fairly successful in this endeavor, however I am not sure how I feel about doing this. This is a financial institution and some of the programs are not in widespread usage out of this type of environment. How do you feel about this? Should IT know how to use all of the programs they install for their organization?