All of these paths resulted in the same class of error. Sometimes it throws in an 'INF' error of some kind just for good measure.
I have seen so many posts on this issue all over the net, offering all the tips and tacks above, and at least one of the steps above have fixed it for every post I've seen. But in my case, nothing has worked.
Does anyone have any further suggestions?
I've also tried the Omega radeon drivers, and apparently they support everything, and those haven't helped either.
I'm running out of things to try, and I may be left with no option but to re-install windows. I'd like to try to figure out what the 'missing file' is, though. If there is a log of some kind that would be ideal, but otherwise maybe FileMon can provide a hint.
I got it working.
Looking back, I had actually gotten to the point where I was going to re-install XP, but my XP cd said "your version of windows is too new...", so essentially it would have required a clean install. Not acceptable. My windows installations are a legacy that I will pass down to my children, and they to theirs. Besides, I simply hate re-installing all the applications. As such, I will patch the registry with surgical tweasers and a bowie-knife before I have to reinstall from scratch; in fact, this is the only reason I still chew gum. So I resigned instead to try to roll back to the old drivers, using the Device Manager property's roll-back button.
After the 20-odd times I tried to install the new drivers, I figured I'd have to roll-back pretty far to get back to the drivers I had installed before the mess began. That was probably correct. In fact, I didn't need to, so I will never know. I rolled back once, rebooted once, rolled-back again (not sure if I even really needed to do this), and re-enabled the drivers. And they worked, right then and there, no reboot required: version 8.20. The latest version from DELL, which I had tried so hard to install pro-actively, only worked when I tried to punt them from the system in defeat.
All the monitor devices were reported working (all 4 of them) as well, and desktop acceleration performance was back to par. There remained one anomaly with the LCD screen only utilizing a 640x480 section when booting to BIOS or displaying a full-screen DOS prompt. This worried me for a bit, but I found an option in the ATI advanced display options to 'Stretch video to fit display', and once I enabled this, all was right with the world, or at least it was so along Latitude 600. And so it remains.
Some other things I learned in the investigation:
This setup process is probably the most frustrating I've ever experienced. There simply must be a bug in ATI's setup, perhaps an implicit dependency on a stale file that "Roll-back" was able to somehow recover.
But at least now I can breathe deeply and sooth my lungs with the ozone emanating gently from what I know to be a machine that isn't entirely broken.