Startup disk has changed

[BlackMac]

I installed ubuntu on my G4/400 with 3rd party processor upgrade and 3rd party DVD burner. Everything works fine except booting. I can boot into ubuntu by pressing the alt key at boot time and selecting the hd with the little tux on it, but it won't stick. In the OS X preferences the ubuntu partition doesn't even show up. Is there a way to select ubuntu as default boot partition?

Edit: This worked after installing ubuntu, but I had to change the startup disk for a while.

[TekMate]

Boot into Ubuntu and try typing ybin in a terminal not sure if this works with Ubuntu not at my machine but I'll double check tonight.