Faaaaar to broad a question, Nick! What sort of bird photography? Flying, perching, single, group, species, location? That's a bit like asking how to edit a portrait, landscape or sports shot. Why not put a couple up on here with an indication of what you're hoping to see?
Many pics will benefit from cropping, levels adjustment and sharpening, so perhaps you could start with those. Also, you don't say how much experience you have with editing. What were you using before CS5?

