Where should I buy a car stereo?

My car’s tape deck finally died, and I need to get a new one, and I need to have it installed for me, as I’m electrically defficient. Where should I go to have it done? We have all of the usual electronics giants here in town, as well as a host of little independent stereo/alarm/tint places.
Where have you had particularly good/bad experiences? Your opinions are greatly appreciated.