If you want to keep your image files organized, and be able to quickly edit vast amounts of downloaded images, then I'd recommend something more powerful like Adobe LightRoom or Apple Aperture 2.
You can download trial versions of either software, so you should try them yourself. Both software have their advocates; it's a matter of personal preference. I use LightRoom, because I used a PC until recently.
Personally, I'm waiting for Elements 6 to ship, hopefully later this month. Before converting to Mac I owned several versions of Elements and the software did everything I needed to do. I'm impressed with the previews of version 6 for Mac and think this will be the best edition yet. And of course, the user interface will be much better on my iMac.
I use adobe cs2 and now cs3 all I can say is dont be scared of them...while they are very advanced it only took me a couple of week to figure out the simple editing stuff...and the advance features are always there if you ever want to do more...which in my opinion when you start editing you always want to do more
Try out Pixelmator. It is not as powerful as Photoshop, but it is certainly more user friendly. And cheaper.
Also check out Lightwave (I think that's what it is called).
As for Aperture/Lightroom, both those are sort of workflow oriented. You can't for instance add text to the image, cut and paste sections and all that.
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