There's a viewer on the Garmin website, looks like Greece is a little bit lacking in places. You can move around and zoom in and out using the controls of the right. A bit fiddly but you can get a general idea of which areas are covered.
My 2011 update DVD should be here this week which will give a better view in Mapsource.
Town called Lamia. On my 2008 Mapsource it's very patchy in its coverage. It would be interesting to see if there's more detail in later versions. Cheers.