Matrox G550 Dual head
I have been using Matrox cards in my systems for years and have always loved them. I am not a gammer, and I use GForce cards for all other systems. I would be tempted to try a dual head GForce if I were you.
If I could get a dual head GForce and a PCI GForce so I could run at least three displays I would try to switch to GForce. I run 4 displays right now with two Matrox cards (one AGP and one PCI - both dual head)