I agree with rek.
Some of you guys need to take it easy. I always ride with earphones on (Sony MDR J10). Always both ears. I have absolutely no problems hearing what's going on around me. Cars, trucks, motorcycles, bikes, people, you name it. I can't recall a time I was caught by surprise. In fact, I feel like my sense of my surroundings is even more acute with music on. Then again, I was one of those guys that studied with my stereo, TV, and computer on, all at the same time. Works for some I guess, not for others. I'd also discourage isolating earphones, like the Sony Fontopia in-ear headphones or Etymotics, since those really will block out sounds that you need to hear.
Anyway, I've found that my Sonys work much better than the Apple buds. Wind noise is reduced (which helps you better hear your surroundings, by the way), and the ear clips keep them comfortably in place. They're very cheap and widely available, so you might want to give thm a shot.