Here are the specs of the unit:
The drive uses a USB 2.0 interface to connect to your PC and is actually pretty slim in its form factor. Unfortunately, it looks like you still won’t be able to mount it inside your case unless your pretty creative.
The price is a bit more than the Xbox 360 external HD-DVD drive, but that of course is a more hacked up solution.
So, for users looking to add HD-DVD capability to their PC, and maybe even their notebooks, it looks like this Toshiba PA35 unit for $369 is the way to go!