do i need an audio interface like an mbox for example?
 

All I want to do is make beats. I have A computer , an M-Adio Axiom pro 61 is on its way, and an mv 8800 beat machine. Do I need an audio interface? I'm not planning on recording vocals any time soon. All the instruments I get will be from the computer or samples.

thank you

No you don't, but without one you'll get latency on your audio, which will make live tracking from your keyboard a nightmare.

I would recommend getting one as the one built into your computer probably won't be designed for anything demanding.