Your best bets:

1 800-800-1020
http://forums.garmin.com/

The phone number is for their customer support, I don't know their hours. If you call them when they're open, you'll get a human within five minutes and that person might know the answer. I've had to call them twice, one time was lackluster and the other time the guy was on the ball and had good answers for me. If not, they have a forum for the 500, full of people who are pretty familiar with it.