You could get pretty much any card and throw on the Matrox triple head to go. http://matrox.com/graphics/en/products/gxm/th2go/ or get one of their multi-monitor cards... I think they do up to 16 at the top-end. The dual head worked pretty well for us on one of our laptops to enable dual screens....
Well if your mobo can handle it, then I'd say get two really cheap PCIe cards. Do you already have the MoBo? What is it?
Do you have 2 PEG (Pci Express Graphics) 16X slots or just one, if you only have one PEG slot and then a buch of PCIe 1-4X slots, then get a cheap 16X card and then an similar 1X card (keep them similar for drivers, although in your environment you might almost be ok with the standard M$ display drivers).
It will give you more options than the Matrox (be sure to not the resolution limits), however since I love Matrox (especially their multi-monitor solutions) so if it fits your needs, enjoy!!