3 monitors on a Radeon 9250 PCI 128 mb

Hi, I currently have a 17″ Relysis TE770 on my VGA output, a 19″ Proview PX-986N on the DVA output (through a VGA converter) and a TV on the S-Video cable.

What I want to do is run both the monitors as an extended desktop, but also the TV as a mirror of either of these screens (although I would accept a further extended desktop if thats all thats possible).

My ATI software only allows me to activate one of these secondary monitors in the “Displays” tab. Is there any way to use all three screens?