We are big fans of The Gimp at New Media Rights. The new version, 2.4, looks slick, and promises to be the best Gimp version yet.
So go get an idea of all the new features, and then upgrade or give it shot for the first time. Hey it's FREE, and it's as good as any software available for image creation and editing.
It's available for free, complete version download for
Linux (Gnome, KDE, Xfce)
Once you've got it installed (simply click the executable file in Windows to install), you can review detailed documentation to get you off and running with The Gimp. Note that The Gimp even has animation ability with its GAP plugin, so the sky's the limit!
This is yet another example of open source software outpacing proprietary models. We've even had internal experiences where staff who were long time Photoshop (made by some company with a name that rhymes with Kanobe) users and now are convinced The Gimp is where it's at for image creation and editing.