Sidewall blow outs are scary. I now carry tire boots just in case- tho Tony says a folded up dollar bill works just as good. If the tube is bulging it will pop in short order, so never ride on it.
Coyote- I also reccomend continental GP4000's. I have had a total of two flats in the 2.5 years that I've been using them. And the first flat- sidewall blow out.