I want something as easy to use as MS Paint. This would probably be paint.net, but I want to explore my options.

For editing existing images I use XnView (http://pagesperso-orange.fr/pierre.g/xnview/enxnview.html) all the time.

For a Photo Shop type program I use PhotoPlus6 (http://www.freeserifsoftware.com/software/PhotoPlus/photoplus.asp).