Edit Suite Advice

I am in need of a new editing computer (tower only) for professional purposes with the following basic requirements:

Dual Monitor (monitors already purchased)

Firewire port

Graphics Accelerator

3rd Output for a preview monitor

Large capacity hard drive (for large projects)

DVD burner

Which would be the most efficient and cost effective? I intend using Adobe editing software (CS4?) so will hopefully not be in need of a capture card.

Your advice  would be much appreciated!