Need to figure out how to record MPC1000 tracks seperately i

Hey guys,
Okay, so... I've been doing beats for a couple years now (on MPC1000), and I'm getting to the point now where I'd really like to start being able to record onto multiple tracks on the computer for the purpose of mixing down later, etc. Now, I know I could just record each track one at a time into the program , but when i record, i really like to be able to manipulate the tracks live as i'm doing, and just do it on feeling. So, at the moment I've just been straight 2-tracking my stuff through a cheap USB soundcard with just RCA L/R inputs. Ideally, I want to be able to record each of my tracks seperately, yet still simultaneously into my computer, so I've gotten a couple suggestions on how I can do this. I was looking into the Alesis MultiMix 8 USB 2.0, because it seems to mostly have what i need. 10 inputs, usb connection, thats pretty clear to me. Someone was also trying to explain to me how you can just, for instance, get a M-Audio Fast Track Pro and just using the midi and spdif, to be able to do the same thing, but i still don't understand how that'd really work. Anyways, forgive my rambling, I just don't know much on the subject, would like to learn more....
If anyone can decipher this message and help me out, I'd very much appreciate it. Thanks!

using the midi and spdif, to be able to do the same thing, but i still don't understand how that'd really work.

Yea, you don't understand it, cause it wont. ;]

MIDI is not your AUDIO tracks.

MIDI is wholly unrelated to SPDIF.

SPDIF is the same signal as your main outs (2 channel).

Basically, you'd assign your sounds in the MPC to the individual outputs (1-4), plug all of those into a multi-channel interface (at least 4), then assign each of those channels to tracks in your DAW.

Arm the tracks, hit record in DAW, hit play on MPC, and that's it.

The exact steps all vary depending on the interface you use and the daw you use.