CrossFireX + Triple Monitors

[TotalLamer]

Now, I know you can't run 3 monitors with CrossfireX. My question is this. I just got together a new rig running 2x 4870x2's. My plan is to run my main monitor off of this, and then add in an el cheapo card like a 4670 to run the two secondary monitors. Will this work? This is my motherboard:

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131361

I know I have room to fit another single slot card in one of the free slots, I just don't know how it would work as far as PCI lanes / drivers would go...