The thing about keys is that it's not just the chords themselves that make the difference - it's also the voicings of them. I have often found, when playing in covers bands in the past, that if I transpose a song I have often needed to make changes to the actual arrangement (chord inversions etc) in order to get it sounding "right".

Incidentally, I just found this website which some of you might find interesting. It discusses the moods supposedly inherent in the various keys.

http://www.library.yale.edu/~mkoth/keychar.htm

Life is exactly what we decide it is in any given moment