CakeAlexS, yep I have one but haven't fitted it, partly because I was waiting for drive prices to drop a bit / get bigger.. you can also get a kit to make the dvd external usb also.
it's easy enough to fit as I replaced a dvd drive.. it's just 1 screw holding it to the laptop case.. an acer in my case.
NI komplete is very big, as are other sample based things.. so yep it eats drives like no ones business. it's kontakts libs mainly..
also dunno if it still applies, as it does with earlier komplete's... but do a search for "pdf" and you might find a load of french / german etc pdf's that just fill up drive.. that you can get rid of.. unless of course you speak them languages also..
this will show you bloat area's , you might want to have a look >
http://www.jam-software.com/treesize_free/