XAMPP 1.7.3 for Mac does not let me run the FTP component.
XAMPP Cannot run FTP while another FTP server is using Port 21.
I'm not running anything else FTP related. I'm on Mac OS X 10.6.4.
Do you have Mac OS X's built in FTP server running? (Check under Options... in File Sharing in the Sharing Preference Pane)