Unfortunately, my laptop (model posted above) uses the older style ADB-connected trackpad, and the Linux drivers for it are poor, to say the least. I've considered updating them, but honestly haven't had the time, and since I'll replace this thing soon anyway, I probably won't bother.

I'd tend to agree, but the version of compiz shipped with natty is a disaster. I'd recommend maverick, or even oneiric if possible. Or even a distro more focused on reliability.