If you're looking to record your friend's band, you'll need a multi-input soundcard like the MAudio Delta 1010
. And if you want to do a full mic'd drum kit, you may need two of them (that'll give you 16 channels). You'll need a very fast computer to deal with this much I/O, and you'll need a mixer that has enough direct channel outputs to hook to the soundcard(s).
Not to discourage you, but you'll be looking at probably a minimum of $1500-2000, and that's assuming you already have the computer to handle the task. You'll need the card(s), the mixer, enough mics to do the job (don't forget the drumkit), a set of reference monitors to mix on, and enough cabling to hook it all up.And maybe some sound isolation material to try to control the live environment a little.
Recording a whole band at once is a much bigger and different deal that setting up a small project studio for one or two people to do a track or two at a time....