I own Photoshop, Adobe Lightroom, have Ifranview and many others but use Picasa for 85% of my stuff. I generally try to take decent pictures right out of the camera but occasionally I need to tweak the color temp or contrast, crop or add some fill flash.

I have another cover shot this coming month and all I used was some minimal Picasa.

I honestly have not found a better software for cataloging my photos, viewing them and doing some simple manipulation, and it's free. I actually bought a Mac specifically for photography but came back to my PC and Picasa..