but take a look in the Preferences of GB and see if the 5 seconds of silence is a setting that can be altered.
Every time I make an audio file in garageband and export to iTunes, it adds a good 5 seconds of silence to the end of the file.
That's all well and good but I don't want the silence. The best solution I've come too is opening it in quicktime pro and then cutting it down there. But I have a file that the computer always sees as a video file(plus s its really hard to cut audio without seeing the sine curve of the audio waves)