Being seen and abiding by the rules of the road is far more important than thinking that a helmet alone is enough. I've seen cyclists wearing helmets dashing through red lights which is a contradiction to say the least..
I'm not sure i agree with your earlier comment though. As a driver, the last thing i pay attention to when i'm driving is whether a cyclist is wearing a helmet or not. So i can't see how it would change other drivers attitudes.
@OP, You'll get used to wearing a helmet, just try a few on and get one that's most comfy.