GarageBand 2: TRY A LOOP WITHOUT COMMITTING TO IT

Sometimes a loop sounds great by itself, but when you drag it up into your Timeline and play it with everything else, it just doesn't fit. Well, here's a great tip for trying out loops with your song, without having to add them to your song first. Just click the Play button for your song, then click on the loop you want to try (in the Loop Browser). In a second or two, you'll hear both your song and the loop, which is automatically synced to your playing song. That way, you can hear if that particular loop will work before you actually drag it up into your Timeline, find out it doesn't work, and then have to delete it.