Side issue (but related).
I realise 'Google Earth' does more, but some don't seem to be aware that many of the most commonly used features - maps, satellite imagery; even the new
Street View - are all available via web based
Google Maps without the need for another 35Mbs in your Program Files.
NB: From a UK based perspective (can't speak for other countries)
this rival is a far better bet on the satellite front, particularly in the areas that encompass 'Birds Eye View' (if you want any convincing try Portsmouth Harbour [UK]; select 'Aerial', zoom right in and go to 'Birds Eye View' [one of the two icons]. Left-click hold and move mouse to navigate image. You can even spin in any geographical direction in this mode via the compass that comes up after selection). This is no ordinary satellite imagery; but supplementary high quality aerial photography.