Thanks, but I already have them in the iPhoto library. I was wondering if there was a script that looked into the library, and compared it with a given directory to look for identical filenames?

This might work ok if you've got only a few thousand photos, but one directory with every single photo you have will quickly become horribly unwieldy. If I were to do it, I'd be mixing all different kinds of photos in to one horrible hodgepodge that makes everything far more difficult. Mixing thousands and thousands of wedding, sports, landsacpe, vacation, and snapshot photos in to one big mess would not be pretty, even if everything was tagged and searchable (I assure you, if I were to tag my photos, it would take a month)

Furthermore, burning DVDs is a poor backup method if you want a "true" backup. If you want to suggest a proper backup, a hard disk is better, because you know if it breaks, whereas with an optical disc, you'll run in to situations where suddenly 3 years later your old backup disc can't be read, and if you didn't check it every few months, you would be pretty much out of luck.

The best backup solution is something that automatically copies your files to a backup drive, which is optimally an external hard disk, but can be a tape drive, DVD, or anything else - but if it's one of the latter, you need to be able to check their integrity on a regular basis if you care at all about data security. It's OK if your backup fails as long as you know it failed, and the backup is backing something up that you already have stored somewhere else. Best, of course, is having your data in three places. you could use the hard disk in your computer as "normal" storage, a backup external hard disk, and DVDs as a *failsafe*.

There's nothing more deadly to data than a backup which has failed... and the user doesn't know that it has failed.

Both Vista and OSX have automatic backup tools that work perfectly. Use them!

Thank you pacodg, but as I mentioned before, the problem here is that the photos are already in the library.

Teff, I completely agree with you. Best way to backup is to do it in a hard drive, I guess that is why I got into this mess :)