In the past if you wanted a high quality scan you either had to pay a lot for a drum scan, or buy a dedicated film scanner as flatbeds were not really that good. However the most recent flatbed scanners, such as the Epson V700, are rather good. You will find some excellent scanner reviews at
www.photo-i.co.uk.
I use a Minolta 5400 to scan Fuji Provia 100F and Kodachrome 64. As Mike says, it uses ICE to remove scratches and dust and I see no reduction in image quality.
To get accurate colours for a given emulsion I created a profile using a Q60 slide from
www.coloraid.de. Unfortunately I could not find a source of Q60 slides for Kodachrome and consequently scanning Kodachrome is a pain as I have to adjust the scanner RGB levels manually.
I also own a cheap Epson flatbed scanner and I was surprised to find that it gave accurate colours (to my eyes) without the need to create a profile.
This might be a characteristic of flatbeds.
I also use a digital camera to copy slides. I bought a Nikon ES-1 slide copier which I attach to the front of a Nikon 60mm macro lens mounted on a Nikon D200. I insert a slide in the end, point it at a light box, and take a photo. I find that the quality is superior to the scanner as the camera has better dynamic range. The only catch is that the ES-1 is designed for use with a film camera, and so to prevent the slide being cropped, I had to add some extension between the ES-1 and the lens. I did this using 5 used glassless filters. (It took a surprising amount of force to smash the fliter glass.) I find it a bit fiddly to use the ES-1 as it has a tendency to collapse (it trombones) and adjusting the slide position is not easy.
If you don't want to buy an ES-1 (~£60), you can simply mount the camera on a tripod, and point the camera at a light box. Getting the correct separation is a bit fiddly. Make sure the room is totally dark apart from the light box. Oh and use a Rocket Blower or similar to remove dust from the slides.
I have some example scans using the Minolta 5400 and the D200 + 60mm lens + ES-1. I can post some crops if anyone is interested.
Leif