About the system partition: In the process of preparing to install OpenBSD, I set the 'IBM Predesktop Area' BIOS option to 'Disabled', expecting a hidden partition to appear. Imagine my surprise when only the NTFS partition (it came w/ m$ poop installed), which filled the entire disk, was visible. Did IBM really put it there?
Either way, out of expediency, I blasted the whole thing to make room for OpenBSD. It seems to work fine, no error, and pressing the 'Access IBM' button during boot now brings up a small, textual boot menu, including an option to enter the BIOS setup. Yay! --schaafuit.