Now that the driver has been installed, we'll need to connect the GPS and let Windows/Mac detect it before the updater can continue.

Using a USB cable (you don't have to use the one that came with the GPS, any one will do), connect the GPS to the computer, and wait until the computer finishes detecting it (30-60 seconds)

For some reason every time I connect my nuvi to my Windows Vista PC, the above dialog box appears, asking if I want to fix potential errors on the drive.

If you see this dialog, make sure you click on "Continue without scanning"

After the PC has finished detecting the GPS, the AutoPlay window may appear. If it does, just close the window by clicking on the red X in the upper-right corner of the dialog window.

Now that the GPS is connected and recognized by the computer, click on Next to continue

Enter the product key found on the green sticker on the back of the DVD case

Sit back and wait - on my system, updating the maps on a nuvi 660 took 1.5 hours

About 1.5 hours later, the update is complete. You can now disconnect the GPS and click Finish on the computer to exit the installer.

To verify that your GPS has been updated to the new "City Navigator North America NT 2008" maps, disconnect the GPS from the computer, power it on, tap on the wrench icon -> Map -> Map Info

Now that your GPS has the latest available maps installed, it's probably a good idea to update the firmware too. Be sure to visit Garmin's updates page and make sure your GPS is running the latest system software.

So how to the updated maps impact Garmin's routing logic and POI database? Be sure to check out the head-to-head routing test between Garmin's older (v8) and newer (v9) maps.