hey Zona,
good luck with your test! you're def going to kill it so try to be relaxed, focused, and rested (i was def relaxed and focused, but i could only sleep 4 hrs the night b4 the test!)
I thought doing the practice test was great...i knew what the place was like, my testing room, and even the tiny cubicles with their pretty bad monitors. if you decide not to do the session (running out of time, etc), ask a friend who tested at your same center to give you a lowdown on the place. if you havent done the free 150 ?'s at all, I would suggest doing them...yes, they're not what you'll see on test day, but the interface is the same, the lab values menus are the same, even the exit buttons are the same, etc and since the questions are not of the UW level of difficulty, most students feel more confident after the 150. good luck!