Depends on whether you'll be flying only the NG or the "Classic" or both. The classics are too loud for me(at higher speeds) so I use the Sennheiser noise cancelling headset for both. Works great. But if you were only flying the NG, you could get away with an earpiece. Also, do a search for this topic. It's been talked about alot before and it's how I made my decision on a headset for the 737. Good luck!
Fly