sludgedragon,
If you are planning on watching DVD movies on your Lombard, OSX does not support DVD Player on the Wallstreet or Lombard, nor do the third-party players for OSX offer an acceptable picture. If you want to watch them booted to 9.x, you need a DVD-ROM drive plus the DVD hardware decoder, either via the decoder on the logic board or a DVD Decoder PC card.
To answer your question on logic boards, the only difference in the two logic boards is the DVD decoder; in addition, both the 333MHz and 400MHz CPUs can run on either logic board.