It's been a fun and harrowing experience thus far. I just installed Hardy--that automatically fixed the boot problem and also got my network running right again. So that's good news.
The sound is still wonky, but I found that's a very common issue with TiPowerbooks, so there's next to nothing I can do about that.
I'm having a very odd graphical glitch where these black pixels appear in the top menu bar. They're pretty much always there, too. I'll try to look and see if anyone else has that problem, but it's certainly not a showstopper.
I'm having trouble with getting java/flash/etc to work in my browser. Maybe they aren't going to work on the PPC. I'll look up ways to do that on my own time, but I appreciate all the help you guys have given me.