Problem with iMac mouse. No rotating

Hello

Few days ago I bought a new iMac Intel 10.6.7 64 bit with cordless keyboard and mouse… I have try everything but I can not rotate my Blender object with the mouse.
Do you know how to do. I dont have that problem with my old mouse .
thanks in advance
http://i1023.photobucket.com/albums/af353/Spender19/Skrmavbild2011-05-09kl164822.png

http://i1023.photobucket.com/albums/af353/Spender19/Skrmavbild2011-05-09kl164905.png

File / User preferences / Input, select “emulate 3 button mouse” tickbox

Thank you Richard. This work perfect.