If you have the HD, you won't need the CF card (with OS1 or OS2). You will need a CF card to load any updates that Akai will push after v2.11... but don't hold your breathe. I'm going on a hunch and will say, once you see what either OS can do compared to 2.11, you will go with an HD and only use the CF card here and there.
I gotta clue you into something also.... read these forums (even page 3,4,5,6,7,8, ect...) and try to refrain from search-able questions. Me and others here frown on some questions and will only get you cracked on and left to fend for your self. Your question is a completely search-able query. Sorry to hit you with this so early in the morning...
Have fun with your machine when it gets to you.
We all want PEACE, but it's to much to face and too far to reach" -Freedom of Speech~ATL.