apple id

I have an apple id I have had for a long time. It was an aol account that I no longer have. At some point I changed the email association to my current email but now that iCloud is here, I can't back up to the cloud because it can't verify the apple id. If I try and change the id to my gmail account I get a message that the gmail account is already associated with an apple id. I am now lost on what to do.