[AccessD] Continuous Form Issue

A2003

I have a bound continuous form that has an Option Group and a Combo Box.
What I would like to do is to update the Option Group and change the
rowsource of the Combo Box without changing the other records.
The purpose of the continuous form is to represent hardware and software
line items on a purchase order form.
The Option Group has two option buttons labeled HW and SW.  
I need to change the rowsource using the option group buttons between
two different queries without changing the other combo boxes on the
continuous form.
Is this possible?

MTIA

Jim