Dropbox is very careful to not overwrite stuff accidentally -- it will save two copies (
name-of-pc's conflicted copy on
date).
The techy way with personal rsync backups is to do an every-five-minutes snapshot so you can go back in time to any five-minute period. For added paranoia, save this on a remote hosted server, or private website, in addition to having your own computer using a RAID configuration.
