my two scents out of years of experience being a musician then later becoming a recordist.
if you're looking to record simply for documentation, then your on board sound card will do or the USB fast track. (learn about latencies)
if you're looking to produce music from your room, that's another story.
i've met a lot of musicians who think that they can be recordists at the same time, invested in a lot of equipments ended up not using them anymore or selling them.
being a recordist/sound engineer/technical producer is a whole different ball game. patience and a lot... and i mean really loooong hours on the desk, is what recording and mixing demands.
so before you jump the gun, play around with what you have. do some multiple takes using your lone sound card. try mixing, play with effects.
if you have the calling for bing a recordist/musician... you will want more. then you consider buying serious equipment.
