Fields

Please tell me how to do the following:

I have one field where a division will be selected by user. Depending on which division they select, I want the next field that holds program choices to filter based on what is available to that division.
example:
If user selects Division "MMH" I want the next field "program choices" to be a pick list of only their designated programs. I want them to only see products based on who they are.