Hi, I just want to post some additional information. I have two machines I tried this on,

a 1st gen Macbook Pro (2.16Ghz core duo, 2gb ram, 256mb ATI Radeon X1600, Mac OS 10.5.1)
a Mac Pro (two 2Ghz Xeon 5130's, 6gb ram, 512mb ATI Radeon X1900XT, Mac OS 10.5.1)

I wasn't getting any crashes but the graphics were so garbled on both that I couldn't see or do anything. Here's a screenshot http://loveturtle.net/stuff/ps/ps-garbled.png
After adding these two lines to psclient.cfg the graphical glitches were gone on both machines and everything appears to be fine (i only played for a few seconds). Here's a screenshot after the changes http://loveturtle.net/stuff/ps/ps-fine.png

So, Anyone experiencing horrible graphical glitches on Mac OS should try this out.