Can I have Paint.NET on Linux yet?
But honestly, spend a weekend learning Gimp. It's a pain, yes I know, but I'm really glad that I did. The official tutorials are wonderful. You'll be able to do so much more, and do it so much better, and even a bit quicker than you could in Paint.NET that you'll wind up preferring Gimp even in Windows.
Just be sure to use single-window mode.