I have just gotten used to garageband and wanted to to record with something better than the buil-in mic on my ibook. I got a Griffin imic, and the computer acknoledges that it is in use for the mic input but then when i try to record on garageband it is still using the internal mic. How do I make it pick up the mic and only the external mic attached to the imic?

Set GarageBand's internal preferences to record via Line-In. GarageBand's preferences are different from Macintosh 10's.