I play bass in my band and we are doing a cover night. One of the songs I need to learn is "Let's Go" by The Cars.

http://www.youtube.com/watch?v=ExYsh1W22Wo

My guitarist says we are going to play it in the key of G. No idea how to even go about figuring that out. I know how to play it normally though. The song starts out by riding an A. I figured G is a whole step down, so can I just play the song a whole step down and it would be in G?