Elektron Musical Instruments

I am about to make the leap and buy a MD, only I have a software-only
background and need some very basic hardware advice...

So basic in fact, that I need to know how to route MD (i.e. and with
what kind of cables )into my Powerbook and then to Ableton Live. For a
sound card I have been considering either an Indigo io, M 410 or a 828
MkII. 
I probably won't be using any other hardware besides a MD, so I wonder
if  the 828 is too extravagant for my plan, especially considering the
price.   

A friend recommended a Mackie mixer to go along with the M 410, but I
must admit I don't have a clue as to why a mixer would be useful --
really my only mission is to route MD into Live.

Any help would be much appreciated.

Jonathan