I'm a part-time photographer, so I have lots of photos. I store my photos on external hard drives. Lots of RAW files and JPEGs. When I first got my Mac, I wondered why it took iPhoto 6+ hours to sync with my photo library. Then I learned that it makes a copy of every single file in your photo library. So my 320 gig Hard Drive is now down to 90 Gigs, thanks to iPhoto. On my PC, I would casually use a program called Picasa (made by google) for simple viewing and slideshows etc. When I would sync photos with that program, it would view them off of my external HD, and not copy them to my computers HD. If the external HD was not hooked up, it wouldn't show any photos in the library. But when I plugged it in, it would see the photo library. Is there an option in iPhoto to do the same thing? I don't want triple copies of all my photos eating up all my HD space. (One original, One backup, one on the Mac HD) Please help a Mac Newbie!