yeah... as far as i know, unless something has changed from our os 9 days, you can't erase your boot volume. if you want to wipe that baby clean, you either need a second hard drive, or i'm guessing (someone wanna pitch in here) that you can boot from your x.2 or x.3 disc and run the utilities from there. then you should be able to 'ungrey' those options...
matt