My opinion:
Write an outline. Kinda what refalm said, but I'll take it to the next level here.
1) Think about licensing and open-source, and all of the stuff Refalm said.
2) Open a project with sourceforge
3) Map out a stuctural diagram of your OS. It will be complex, but it should be, because OSes are complex.
4) Decide which language you want to write each piece in. Some parts should be portable (easy to port to other platforms), some parts should be fast. You have to make the distinction as to what should be written in what.
5) Code, compile and test the bootloader.
----DO NOT PROCEED PAST HERE UNTIL EVERYTHING ELSE ABOVE IS DONE----
6) Start coding the core OS, and IO systems.
7) Compile, test, and debug the core OS and IO systems. Get the OS to load from the bootloader This process could take months...
7) Build on it from there. Don't be afraid to include other people's code in there if their license allows it. Why recode what others have already done?
PM Me if you need more help/guidance.
Post updates here too.
[ April 04, 2003: Message edited by: The Muffin Man ]