I haven't done my first commute of 2008 yet, planning on that tomorrow morning but today I had my first spill for many many years. 200 yards from home I came off on some black ice. My head hit the road, I was wearing a helmet (no need for discussion) so my headache was not as bad as it could have been, bruised my elbow and thigh. The helmet is scratched but I cannot detect any damage to the styrene shell. Should I replace the helmet? If yes, what sort should I get?