http://www.dotpdn.com/downloads/pdn.html 
I pulled down a copy of 3.5 and installed it.  All the others seemed to tie into an installer package with nagware that I didnt feel like dealing with.  Once it was up an running it came across a lot like a lightweight Photoshop.  Unfortunately, the help is all online, so, that is a little annoying, but, its still a good application.
http://www.getpaint.net/doc/latest/index.html 
In a way, it reminds me of Gimp, but, more useful and .NET oriented.  In the end, I think Ill be investing some time into it.