Zee fits the alphabet rhyme (Ay, bee, see, dee, ee, eff, gee, etc).
Zed does not.
You dont say "Ay, Bed, Sed, dead, eff, jed,...." do you?
So WTF is up with "zed"?
Ergo we Americans say it right!
So get with the program already...you Brits (the few of you who never watched Sesame Street).
Zed's dead, baby. Zed's dead.