There's not much difference between those speeds, although, I think the 2.16 is the newer model is it not? larger HDD and stuff?
As for playing HD DVDs or Bluray, there is currently no hardware support nor Software support. So even if you rip the HD DVD to your HDD from another PC, you can't play the HD DVD (as of yet). It can however, when support comes, play 1080p AVC content without a hitch...