http://support.apple.com/kb/HT3964
Apple had a download that specifically addressed issues with fans in MacBook Pros which may have also included MacBooks, but good luck finding it on their terrible support site... Come to think of it, it might have been a SMC update, so there might also be one for the MacBook.
Also, this may sound like it isn't related because your fans only run when Live is running, but you might want to clean the vents to the fans -it can't hurt anything.
