Thanks everyone for the education on PIO mode. I am sure that is the mode this HP system was using!
Update on this HP Maxtor hard drive issue:
You probably need to use a PS/2 keyboard: older systems don't see the USB keyboard in the BIOS (the Ctl+Alt+Del combination sends an interrupt, not a conventional key code, so it will work regardless). It is possible there is a setting to make the BIOS look for a USB keyboard instead, but you will need a PS/2 keyboard to enable it
Well went down to Frys and bought a PS/2 keyboard thinking that would fix the problem too, but it didn't work. I still get stuck on the main BIOS screen and can't move around to change anything. Here's one new bit of news: when I placed the Maxtor drive in my system to run Spin Rite, the program reported, "Invalid Partition for Drive Size" and the lettering was all "red". Ok, well I decided to put the drive back into the HP case and use the PS/2 keyboard but now the drive won't even boot up...it just freezes on a blank screen with a blinking cursor. All I want to do is change the bootup sequence to boot to the CD drive in order to format it and reinstall XP (there's nothing important on the drive).
Does this sound like something is wrong with the motherboard's BIOS...which might be the reason the partition table got messed up to begin with? Or, should I install the drive in my other system again and reformat/reinstall XP there?