Update Text box with variable from drop down

Hello,

I have a form where a user has a drop down menu that is generated from a sql query.  Based on whatever the user chooses, i would like to update another text box from the same query but different column and have it display in real time. For example, a user chooses Adobe Reader to download, but has a price, i woudl like the price field to update and display when the user chooses Adobe Reader.  I have 1 query that pulls all the information for the applicatoin, and i also have another query that will only pull the price of the app.

How do i have workflow auto update and display the app, relative to the selection in the drop down?