Many places don't seem to care.
I got an external DVD-RW for our Powerbook with the OEM copy of XP Home I purchased, but Newegg doesn't seem to require a hardware purchase with it.
I bought an OEM copy of WPOffice on eBay a while back. They claimed they had to ship a splitter or some other nominal piece of hardware with it, but it wasn't in the package.
Have a look around. You should be able to get a legitimate OEM copy pretty easily.
Cheers,
Scott.