Power PC trouble

[Rory]

iMac G3. Slot loading with 128mb Ram. Hope thats enough to know which one i'm on about.

Yeah. I tryed installing Ubuntu 8.04 on it. Yes I got the PowerPC version for it.
It keeps throwing an X server error at me.
As a back up I "got" a copy of OS X 10.2. Would it install?

Could anyone help with this. I prefer Ubuntu over OS X. So that would be my first choice.

Thanks