This is my first time and I’m going to use C#/XNA, Paint Shop Pro, Gimp, Inkscape and ACID Music Studio.

I forgot to mention that I probably will use Farseer in my game: 
http://farseerphysics.codeplex.com

So, I’m in and I’ll use: C#/XNA, Paint Shop Pro, Gimp, Inkscape, ACID Music Studio and Farseer Physics.