The things you hear on the news are really no different than the stuff that happens in the U.S. If you stay out of the bad areas you will be fine, much like you wouldn’t take a vacation to the bad part of a major city in the states. One thing that may throw you off is that Mexican military and police have check points on all of the major highways in order to try to prevent the drug trafficing from South America. You will also notice that the police are armed with machine guns and are very prevalent. That being said, I would take it as a reasurance of safty and not fear. Most of them are very nice, but very business oriented. The stories of bad cops and such are almost always up near the US border where day tourists go.