Scanning in 4"x6" photos--what resolution?

[anonymouse1]

I'm going to scan some 4x6 photos, so I can clear out some storage space. Any idea what resolution to scan them in at, if I might want to print them out someday? Does it depend on whether I want to print them out later as enlargements; say 8"x10"? Is that even worth it (would there be too much grain?)?

Thanks.