HD 5850, 3 displays

I also need to connect 3 monitors to my Radeon HD 5850

My Monitors are

Left and Right = Dell E193FP (VGA)

Center = Vizio E280i-A1 (VGA, HDMI, Component,)

Currently HD5850, 2 outputs DVI-I Dual Link  ports are connected, 1 each to adapters and then 1 each Dell E193FP monitors. 1 output Display Adapter is hooked to an adapter (Display Port  to VGA) then to  Vizio E280i-A1 (VGA)

I believe that the adapters that I use do not satisfy the requirements for triple monitor

Do I have to use monitors that have the specific input without adapters?

Multiple monitors option not available with Radeon HD 5850