The problem with slides is the small size (I'm assuming your'e talking about 35 mm slides), so you need a much higher resolution than a normal flatbed scanner is capable of. You can scan it on a flatbed at a few hundred up to a couple thousand dpi, and it will probably turn out ok for your use, but if you're looking for the best quality, then a drum scanner goes up to 10K+ dpi. If there were only a few slides, and you want high quality, it's probably just better to have it professionally done. If you're just copying a lot of family pictures and dont' really care as much, then a regular flatbed will be ok