I attempted to re-install ESXi again. Now that I have a separate system in which to run the vSphere client, I'm hoping I can get some actual use out of the box.
In any case, the 4.1 install didn't work. It would boot but would fail early in the install, claiming that it couldn't see my CDROM. 4.0 did install and I just now downloaded the 4.0-to-4.1 upgrade, so I'm hoping that his will work.
What I did manage to do is come up with a pseudo-quad boot, so that I can run either ESXi, Ubuntu 10.4, Windows XP, or whatever I have on the fourth drive (it varies over short periods of time). This is accomplished via BIOS, which allows me to enable/disable SATA channels and also allows me to change the order of the hard drives that the box attempts to boot from.
I didn't even have to resort to adding drivers to the install disk (though I still have those disks). I'm hoping 4.1 installs without deleting the stuff that works now. We'll see. More later.