Hi, I was wondering how hard it is to make firmware for the NXT. Also, what language would you need in order to do this? To start with, I don't mean making the most complex setup ever made. Just start at the beginning with a system that would boot, and go from there. Thanks!!

If you've never done something of this magnitude before, very!

I would start by taking a look at the source code of the Lego FW. It's written in C. Indeed it is very involved, and as far as I know there are no tutorials on the subject.