I used Fireworks for years, then when I lost my copy I began using Paint.NET. I used that for a year and liked it a lot - but a little while ago I had the chance to get a free student copy of Microsoft Expression Design which I decided to use instead seeing as it was a design application worth a couple hundred dollars. Perhaps it is better - I really wouldn't know, for me personally I didn't like the UI much at all and I don't need particularly complicated functionality.
I gave up on that and decided to give the new updated Paint in Windows 7 a go - after all, like I said, I don't need particularly complicated functionality. However now, after a couple weeks of that I have to wonder - how did Rick Brewster manage to create an application which is so perfectly combines a simplicity with the additional advanced functionality when needed? It perfectly suits people like me who need a lot more than simple cutting and pasting, but don't need all the extra advanced functionality of programs like the Gimp, Photoshop or Expression Design. Not only that - but Paint.NET is tiny, fast and stable - something I really couldn't say about Expression Design.
So I'm back to using Paint.net and loving it =) looking forward to future releases.