If your rotors are very badly grooved, turn them. Otherwise, just install your new pads. Turning rotors is a peculiarly American thing to do. Most European mechanics just slap the pads on and have at it knowing everything is just fine.
I'd like to know where the idea of turning rotors at every brake job came from. Does anyone here know the answer? My suspicions lead me to believe it comes from the mass marketing of automotive services. Pep Boys, Sears, whoever, advertise a brake special and adding turned rotors seems to attract customers.
A few years ago (now that I think of it, quite a few years ago) I dropped a car at a service shop for brakes. The Service Tech called with the bad news - my rotors needed turning and the price of the job was going to increase by over a hundred dollars. Since I usually did my own brakes, I knew the cost of turning rotors was about six bucks each, if that. I told the bastard, "Don't do a thing, I'll be right over to pick up the car."