My father recently sent old family slides off to be professionally scanned, and the results were pretty good. Most of the professional services use Nikon scanners with their "Cool ICE" technology, which basically uses a fourth wavelength of light which tends to highlight scratches and dust, which can then be automatically removed.

Frankly, life is too short to spend it feeding a scanner, and life is *way* to short to remove dust and scratches in Photoshop. Shelling out the bucks to have somebody else do it is very, very attractive.