A couple of years ago I purchased a Polaroid neg/slide scanner, and it works an absolute charm.
My first effort was a flatbed scanner (AU$150) which had a light box for neg scanning. It was useless.
Next effort was a cheap (AU$450) negative scanner, which worked OK, but the colour definition was very ordinary.
Third and final effort was the Polaroid Sprintscan 4000, a 4000dpi negative and slide scanner. Cost AU$4000, but it should have been my first purchase.
There are a lot more around now, at much more reasonable prices. But if you plan on buying one, make sure that it has a slide tray which can hold at least 4 or 5 slides at once - it will cut down on time/effort required.
As far as resolution goes, a 2000dpi scanner will give you prints up to about 15"x10". If you want to make larger prints, or blow up a small part of a photo, make sure to get a 4000dpi scanner.