If your yaboot isn't busted but just the OF boot path, try booting with option key down. If yaboot boot partition isn't in a too bad shape, you should have one of the choices there with a penguin that will lead you to yaboot. From there, boot linux. From linux, re-set the boot partition (ybin might do it, if not, mkofboot should). If yaboot is too busted, boot the distro CD and restore things from there. Ben.