what do you have? do you have a mixing desk? how much money can you spend?
if you want it to be good quality, it won?t be that supercheap, sorry. you might need a soundcard (A/D converter), a sequencer, maybe a seperate audio recording program, and a midi interface.
i can?t tell you much more without knowing what you got and description of your computer. how many tracks do you want to record? how professional do you want it to be?
to do it good quality (my standard of good is being able to cut an album), prices for the soundcard/ converter range from about 700 $ upwards. i can recommend a RME Hammerfall (DSP, plus multiface or digiface), which is a great interface. a soundblaster or whatever is a gaming card, not professionally used for recording. sequenzer, i would recommend cubase (ask your dealer for nice price or copy it), since logic will be only supported on the mac platform in the near future. there are plenty of okey midiinterfaces for about 100$, if one midi in/out jack on the soundcard (which it maybe should offer) are not enough (16 channels). cubase can record audio, so you won?t really need protools (which is studiostandard, but prices range from 10k upwards). what you need is a fast computer, enough RAM and 40-80 GB fast harddisk for fine multitrackrecording.