@cobra
No offence, and I don't want to sound negative, but do your really know what you're getting yourself into? Writing a complete OS is extremely hard. Look at it this way, AROS project have been continuing for many years and is nowhere near complete - and it's not a one-man effort. *And* they are using the current AmigaOS as a template.
If you do try this, I wish you the best of luck. You'll need it. ;-)