A quick word of caution regarding trashing the 9.0.4 Enabler. I do not know how much this affects other machines, but here is what I found with my 7500/100 (now more of a 7300/200).
I installed the 9.0.4 update to my machine and it would crash within 5 minutes from startup, no matter what I was doing, whether it be running an app or just sitting at the desktop. Starting with extensions off, the machine ran fine. I trimmed down the Extensions Manager to the point of only a couple 3rd party extensions along with a slimmed-down set of Apple extensions. This still didn't work.
I then looked in my System folder and saw the new Enabler that was never there before. I trashed it and restarted. Everything worked great! For grins, I ran the Software Update and it said the only thing I needed was OS 9.0.4. I looked at what my system was, and it said 9.0. I reinstalled the update, and it started crashing again. I threw away the Enabler, and it worked fine, but the System said I was only running 9.0
I do not know what the Enabler does, but it seems to want to be there for the OS to see itself as 9.0.4. Now I am just running the update without the Enabler, and everything is running fine.
Just my $0.02