Deep Vein Thrombosis -- Recurrent Event - I recently had a large DVT following long car ride?

and had a PE (likely starting from a DVT) in '01. I'm 41, active, healthy, and do NOT have any genetic thrombolytic factors. I am currently on combination therapy with Coumadin, Plavix, and Aspirin and will take Coumadin for life. I understand that each drug somehow acts differently to prevent clots, but I also know that combination therapy puts one at great risk for bleeding. Is there evidence supporting combination therapy vs. single medication therapy (Coumadin)?