Are you booting from OS 9 or trying to run
in classic mode? For best UT results, you
should boot from OS 9.
UTX p3 mostly works but has problems.
They are supposed to be addressing this
by working on a real release of UT for OS X.
By the way, I recommend getting UT Game Of
The Year (GOTY) edition. It has more stuff
and I think you don't have to upgrade it
to version 426.