OK, I finally found my own answer. I ran across several earlier posts about a similar issue with different motherboards and one of them suggested trying to load the previous version (4.0) of ESXi. I downloaded the ISO, put it on a USB drive and it installed without incident.
So now I just need to try and run the upgrade to 4.1, but that will have to wait for now.
Just an additional note. I have tried to upgrade the ESXi 4.0 to both the 4.1 and the 4.1 U1 by using the vihostupdate command. In both instances, the upgrade would proceed normally and complete, but when the server was rebooted the installation would crash. I have since re-installed the ESXi 4.0 for now, but I would like to be able to move to 4.1 do to the added USB support that I would like to use.
Yet another update to the saga if anyone is following this.
I found that the main portion of the 4.1 problem was being caused by the memory on the motherboard. If I used the full 6GB (3x2GB) the motherboard would run in what was called "Flex memory mode" and no matter what I tried 4.1 would not work. When I pulled out one of the modules the MB dropped into dual channel mode for the memory and 4.1 would run.
I had upgraded the intitial install of 4.0 to 4.1 U1 with the vihost update command. So I figured I would try installing the 4.1 U1 from scratch. This failed with the same installation error that I had when I had the memory in "flex mode". So I went back to the 4.1 version that I had upgraded from the 4.0.
I then explored some other issues, like the fact that ESXi would not natively support the on-board LAN (Realtek 8111) so I used the driver from here http://www.vm-help.com/esx40i/customize_oem_tgz.php, the Installation ISO for 4.1 U1 (VMware-VMvisor-Installer-4.1.0.update1-348481.x86_64.iso) and a build script (mkesxiaio_4.1.sh) from http://code.google.com/p/mkesxiaio/
Now the script needs to be run on a Linux machine (I used Ubuntu and it ran fine) But I was able to build a new boot image directly on to my USB stick with the drivers for the on-board Realtek 8111 LAN along with the PCI-express Intel GB nic.
So now the machine is running 4.1 U1, with both the Realtek and the Intel nics, 4GB ram with the two 160GB SATA drives connected to a Rosewill RC-209-EX SATA controller for the datastores. The onboard SATA controller and attached drives are are paravirtualized through to my unRAID media server VM (based off this thread http://lime-technology.com/forum/index.php?topic=7914.0) that I am running on the box as well as my DC and other VMs.
That is all for now