Are you printing at home or sending it somewhere to be printed?
I scan images here at work, if I am keeping the image the same size or reducing it, I scan at 300 dpi. You'll have some monsterous files at 600 dpi and most likely you won't see any difference on your print, but it will take forever to print. Do a test run and scan something at a couple different dpi's and see what happens.
If you are scanning for computer use you can do 72 or 80 dpi.