Maybe the answer I'm looking for isn't as simple as I think it should be. I already viewed all the documentation that you pointed me to. The "Guest Operating System Installation Guide" from the 2.x documentation area points to the same document as your second link. This document lists a crap load of operating systems and I see that there are notes on some of the OS'es that state certain requirements when using ESX 2.x. I tried installing Ubuntu 9.04 but after I get booted up to the CD and click on "Installation" it just reboots the VM and I get stuck in a loop where it just keeps rebooting after I click "Installation"...same thing happened with openSUSE 11.1. I am using old PIII hardware so that may have something to do with it. I did get Ubuntu 6.10 loaded up but I can't get the VMWare Tools to install. I'm not a Linux guy.
I just thought that VMWare would have a document that says "ESX 2.5.5 supports these Guest Operating Systems...". I guess there's no such document.
the problem is the ESX 2.5 is end of life, so putting out a supported documentation has no benefit.
You can look through the archives to see what you can find, but not matter what Guest OS guide you find, it will link back to the most current.