CStroman is correct. You can always explore the option of adding a second PCI video card to the mix. The only thing I have to caution is, though you get dual monitor capability, you lose out on some of the features such as DVDMax, Clone, ability to shoot a window to the secondary monitor via hot keys and a host of other items. There are programs out there that may enable you to have these features, but I don't know.
Perhaps get a G450 PCI. Yes, they made a PCI version of the card. However, it is only fully support on Intel system. Supposely, the busmastering on a non-Intel motherboard causes instablilities. I would like to go this route myself in the near future.