Get them turned by somebody that knows what they're doing.  If your rotors are turned with too coarse of a finish then your stopping distance can actually increase, not to mention your pad wear.  Just FYI, I'd be shocked if you could stop your truck with sand blasted rotors without locking 'em up.  Too much traction on a brake rotor is not a good thing.

On a side note, it was mentioned that turning your rotors every time you replace pads is ideal.  The major auto manufacturers don't necessarilly agree, although you should check thickness and wear characteristics to determine whether turning is required.  Minor circumferential grooving is perfectly normal and won't negatively impact performance or pad life once the pads have been seated.  The only thing unnecessarily turning your rotors accomplishes is to shorten the life of the rotors.  Just my