I have recently been converted to a Mac (mini) and it's a lovely little device. I was not impressed with the iPhoto component of iLife and would not spend money on iLife for it alone.
Instead, I installed Picasa2 (Windows) after installing Darwine (not 'Wine'), the only downside of this act was that I have Picasa's flagrantly Windowsy interface to deal with (Fine on Windows but coarse on a Mac

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The problem, for me, with iPhoto is that it makes copies of all pics it finds so possibly doubling the space the pics take up. These pics are in an Apple proprietary format. Picasa's plus is that it only builds an index of the pics it finds leaving them where they were. It will, however, allow you to arrange them in 'virtual' folders if you want, or move/copy them around your hard disk(s) or delete them. I'm doing this through my Mac on pics on two other Windows machines as well as the Mac.
I thought I was having problems installing Darwine - many do - but it seemed to come right as I downloaded Picasa2 and it installed fine! Have a look.
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