Using GPS without Cell Service?

[Black_Death]

I am going to Thailand and Cambodia for a few weeks in May and I think it would be pretty nice to be able to use GPS while there. Unfortunately the normal programs I use (Google Maps and MS Live) don't allow me to download map data, so if I do not have data service it will not show me the map. Do you guys know of a way I can download the maps for use offline? Are there other software options that will do what I want? All I want is something like Google Earth that works while not connected to the internet. If it could show me restaurants and stuff as well that would be perfect.