Selling Linux to AS/400 Shops?

cgh4be asks: "I work for an IBM business partner and each year we host a technology seminar for our customers, most of which have AS/400 backgrounds. I am the 'Linux guy' at work and have been chosen to give a 1 hour presentation to these IBMers about linux. So, my question to the Slashdot community is, what points and information should I touch on in this presentation to make it effective? I'd like to give some history about it of course, but the goal is to get them to start using it in their businesses."