I love techie toys. But I also work in the IT business, so I live by the adages "You touch it... you break it" and "Always have a roll-back plan." The folks at Garmin seem to have more much confidence in their firmware upgrades than... everybody else in the world. If you ever go through an upgrade and find that it doesn't work the way it should, calling Garmin won't help. They'll tell you the firmware is solid and the kitchen table your device is on really is moving at 22 km/h (yes, really, that's what they told me).
I was naturally quite pleased to find this library of Garmin firmware files. To install the version you want, download the file you need, rename it gupdate.gcd and place it in the Garmin folder on your device. Re-start your Garmin and it will install the firmware.
Very nice! I've noticed that the Garmin 510 firmware updates have been really flaky with different disruptions to functionality with each update!