If I move from Mac/Mobile Me email to iCloud, will my current account's email vanish?

Probably a silly question. I am running Snow Leopard and for a couple of days have not been able to send mail from my long-time Apple email account. I have started the move from Mac/Mobile Me email to iCloud, when all I really need is to enable the iCloud SMTP server, I think. 😝

When I was a few steps into the move, I reached the point where I had to either "continue" with my current email address/password, or create a new email account If I follow Apple's direction and "add" an account with my core user info, will I end up with "my" account as iCloud, but with my current account's email "vanished?"

I go back far enough that my Apple user name is not an email address, and my email address is dot.Mac, and I'd like to keep it that way, but right now I just want to be able to "send." Since my problem began I have been writing and then saving emails on my iMac, then opening them on my iPad or iPhone and sending the emails from those devices. Thank heaven for IMAP!!!!

Thanks,

Laura