I want to populate a combobox with a list that displays one field, but has the value of another using the datareader object.

I am able to do this with a dataset and using the displaymember and valuemember properties of the combobox. However, I'm trying to make the procedure run as quickly as possible. Since I won't be updating the data at all, I figure using a datareader object would be faster, but I'm not sure how to populate a combobox with two values (the displaymember and the valuemember) using a datareader. Can anyone help me here?