Get an access virus which has plenty of knobs to keep you happy and a nice custom built audio computer. Run something audio based on the PC, Nuendo is looking like the weapon of choice at the moment on the PC or Logic Audio - but support for this is dead tragicallyon that platform. You'll want to have the most powerful audio thing you can get your hands on in the end.

Get the biggest sample library that you can get your hands on. The MC909 does look pretty cool, but I couldn't face writing a track on anything smaller than a 19" monitor and once you've tried it you'll not want to go back. And if you don't like one piece of audio software on the PC you can always find one you do like ...