Multi-headed display without non-free drivers

I'm using Trisquel 4.5 on my desktop and would like to add support for a second monitor, so I'm currently looking for a way to accomplish this without resorting to proprietary drivers. The Radeon 9200 card I looked at earlier requires non-free software to work; is it possible to achieve the effect using the free driver instead? Or are there other cards that support dual displays by default?