recording sound

i have a 12in ibook g4 (brand new) and i want to do some recording on it...what should i go for for recording? the internal sound will obviously suck and at this point i think my only choice is the griffin PowerWave. Is this thing any good as far as recording quality goes? i know it probably sounds pretty good in playback but it does offer zero-latency recording which is a key feature because i need to playback and record at the same time.

I think use an external mic, and an app like quickvoice, as far as playing and recording at the same time, there are music apps that will allow you to do something like that, or u can record 2 seperate pieces and overlay them in an app like souundtrack, even garageband allows you to overlay tracks in this way.