Backups-Cheap IDE Drives as Alternative to Tapes?

3107813 asks: "Are large IDE drives a good alternative to tapes for backing up a server? I have a server with about 40GB of storage that I backup nightly. I have a tape rotation and end up saving the monthly tapes in case someone comes back and wants a file they messed up. Could I replace the tape system with large cheap ide drives?" The thing that makes tape popular as a backup medium is due to the fact that they are portable. Now that IDE drives are becoming cheaper and smaller, would something like this be practical?