I am running a Behringer 6-channel mixer (which for me is overkill) into a soundblaster audigy 2. Since the sound card only has 1 input, that means you can only record 1 track at a time. If you want to record, for example, 4 tracks simultaneously, you need 4 inputs on your sound card. You can, however, cheat a little bit. What you can do is record a stereo track (ie. 2 channels on 1 track, left and right) and have 1 input on your mixer panned all the way to the left, and 1 input panned all the way to the right. Then once its recorded, you can just split the left and right channels into 2 separate mono channels. But with 1 input, this is the most you can possibly do. Otherwise, everything you send into the computer will sound good, but will all be in 1 track.
Hopefully this helps.
j