William asked about this, and I thought others might like to try it. Keep in mind that some of the older ones wont update unless you pay, but probably all those under 5 years old update free.
1. Download Garmin Express to your Windows or Mac computer.
2. Connect your Garmin device to your computer using a USB cable.
3. Open Garmin Express and click the "Updates" tab to view available updates for your device.
4. You can install all updates with a single click.
Thanks Harry. Mine (nuvi 350) seems to be one of the old ones. It doesn't give a free upgrade.