Hey guys, I can't figure out how to use a new microphone with garageband. It plugs into the line-in part on my gf's MBP (the one next to the headphone port, right?), and i choose "Line-In" from the sound preference pane... but it's still using the internal mic when recording on garageband. I also remember trying to record with my guitar plugged into the comp, and that didn't work either. I'm clearly missing a step. Can someone help me out, please? Thanks!