I've been using iPhoto for years and all my digital photos dating back to 2004 are in there...and I have never renamed the files. Half of them have the wrong date. Something went awry the last time I got a new computer and the order of them got all mixed up, so that photos from 2011 were, say, in the middle of 2005.
I have everything backed up. Just got a new computer and my new year's resolution is to organize and archive my photos properly, as well as upload monthly to Shutterfly/mPix so that when I go to make albums at Christmas for all the grandparents and myself, I do not find myself 10 months behind as I did this year!
All that said...where to begin? Do you name your photo files? A friend of mine files hers by month and I will ask her more details, but thought I'd ask here, too.
I am thinking about switching over to Lightroom or Photoshop Elements, as I believe these programs make it easier to access/organize your original files compared to iPhoto.