If you're looking for the alternate keypad between the QWERTY and the
numberic (arrows, [HELP], [Do], etc.) then, you'll want the LK-style
keyboard. If you use Linux on your x86 box -- and you should ;) --
a few Xmodmap entries and or Xresources entries will give you pretty
much full use of the LK-sytle keyboard. On the Mac, it's been quite
a while since I've plugged an LK-style keyboard into one -- I recall
that it worked pretty much out-of-the-box.
I think Terminal.app lets me remap arbitrary key-presses to any escape sequence I want, I
assume I could use this to enable the Do/arrow keys etc?