Sorry for the delay. I work ridiculous hours.
Anyway, I have been doing it this way for a long time. Find a drum and bass track I like, usually in Guitar Pro, export the tracks separately, import them into Cakewalk after inserting the synths of course. I'm using SD3 for the drums and MODO bass for, well, the bass.
SD3 works fine. I have found that MODO will work until I import the midi. I always have to transpose the bass... Process>Transpose enter 12, done. It's always worked fine until recently. Now it seems to freeze MODO. Again, the built-in keyboard won't even play a note after I import the midi.