Hmmm...Walmart's good for something? 
Hammer
I had WalMart scan several hundred of my slides a while back, and the results were mediocre at best. There was plenty of dust, bad cropping (left or right side cut off), and even though I gave the slides to them in plastic pages, all oriented the correct way, they still managed to scan some of them backwards or upside down. Their lame excuse was that the emulsion was on the "wrong side" (Kodachromes) and I must have somehow shot them that way. Think about it for a second: unprocessed film is opaque. There's no way you could shoot it backwards, even if you could fit it in the camera.
Anyway, after that experience, I bought a midrange film scanner made by Plustek, the OpticFilm 7500i. It's probably not in the same class as the gold standard home scanners, the Nikon and Minoltas, but it was only $300, not $1000+. It has a good honest 2400 dpi resolution and far better dynamic range than the WalMart scans. The dust and scratch removal software works fne for E-6 film, although I still have to do Kodachrome manually in Photoshop.
I have tried using my flatbed scanner (Epson RX500) for slides, but couldn't get a sharp image to save my life. Other people have claimed better results with newer models, but I don't have any direct experience with them.
GTD
