You can get Picassa free from Google – just go to the “More” page from Google’s main page. It’s typical Google-ware – looks great, and does the basics well. Not looked at in a while so I don’t know how it currently stacks up.
I mainly use Photoshop Elements v4, and have found it really good for all my needs so far. I’m barely scratching the surface of what it can do. It’s about £40 – v5 is out now but not found a reason to upgrade.
I’ve heard good things about Gimp – used an early version briefly but found the UI to be lacking compared to Elements.
Paintshop Pro you now have to pay for, I think. Looks like Turks needs an eyepatch airbrushing in on his face 🙂