I did several searches (Google, MSN Technet, Dell Support, etc.) and found several discussions, including the one you referenced, but none provided a solution for me. I tried everything listed, and then some. The Dell technician was obviously working from a solutions database that provided him with a series of items to check and correct. He found something in a configuration setting SOMEWHERE (I've been working with PCs since before the original XT, so I'm familiar with config.sys, sys.ini, autoexec, etc.), but I still don't know WHERE or WHAT he changed (he mentioned something about Windows XP being loaded from CD-ROM.)

It has to be something in the BIOS since it made no difference whether I booted from XP, WIN98 (swapped my two drive designations), floppy or CD. Flashing the ROM didn't help. Must be something that can't be set/reset through the user interface. I know that most of the chipsets provide more configuration options than the Dell BIOS setup allows. The tech was somehow able to scan my BIOS settings and change something -- but HOW!
I suppose I could just call back, and ASK. I was hoping someone here was familiar enough with tech support to know. Guess it will remain a mystery for now.