Thanks for the model of your graphics card. I use two Geforce FX5200 right now to drive my four monitors.
Oh and if you want a nice program to control your monitors take a look at UltraMon program at www.ultramon.com
Its only around $35 and it does many thinks for multi monitor setups I have found.
Looks like I will have to upgrade my mother board. I wish they made more slots like the older motherboards use to have.