What software are you using? Computer and OS? Choosing a souncard is not an easy thing, first there is input/ouput issues, how many inputs do you need? What kind of music are you going to be recording?

If your recording a live band and want to track everything at once but record each piece onto its own track then you would need a soundcard with several inputs.

I can go on and on about this but it would make it easy for you to elaborate on what you have already and what you are looking to do.

Thanks,