Here are some resources about scanning negatives and slides.
If you need to scan old prints, go to Scanning Old Photos.
Mastering Digital Scanning David D. Busch
Steve's Digicams - Image & Film Scanners
Epson V700 Flatbed, film & prints
Nikon Coolscan 5000 Film only
Scanning with Silverfast Mark Segal
Film Scanner for 10,000 Slides Kim Komando
How to Select a Photo Scanner Ken Rockwell
Scanning Basics 101 Wayne Fulton
Scanning Film Norman Koren
Quick Tips for Scanning Photographs Hewlett-Packard