It "can" make a difference if you're really picky about the picture. Most non-videophiles probably wouldn't notice much difference. If it were me, I'd go out and buy a calibration DVD for about $35 and do it myself. Look for something like Avia or Digital Video Essentials (DVE). You can find both on
Amazon.com. I've used DVE in the past. It has everything you would need to set up the basics to get a good picture. Video test patterns for calibrating sharpness, contrast, brightness, color and tint.
Beyond those settings, a professional calibration would take it a step further and actually tweak the color balance using a colorimeter (a device that measures the color output on the screen). It may or may not be a big change depending on how accurate your set was out of the box to begin with. Incidentally, you can't make those adjustments yourself because you need to go into the "secret" service menu to do so and the average consumer can't (and shouldn't) make any adjustments in the service menu.
One big thing to keep in mind is that an accurately calibrated set (in most cases) won't look anything like the set in the store. In general, the sets on display in the store have sharpness, contrast and color satuation cranked to the max in order to catch your eye. A bigger, brighter picture sells better. Unfortunately that's not really an "accurate" picture. When some people are then presented with a correctly calibrated picture, they may not actually like it because it will initially seemed to have lost its pop. Lost its sharpness. Lost its vividness.
If you're going to get it professionally done, I'd check to make sure the tech is ISF certified. If you want some more info about profesional calibration, take a look at the Imaging Science Foundation's website -
www.imagingscience.com.
There's a basic calibration section in the extras.
