Like everyone says, you can have both. I have two at the moment myself, but I'm dumping one when I get all my accounts switched over to the new one.

One thing about AOL: I was with them years ago, and when I left them, they called me repeatedly for months, trying to get me to sign back up, offering me all kinds of deals, even if it was just a $4.95 service. They were a good service for me, and it was nice to have a backup, but just be aware that if you unsubscribe from their service, they may be a pain about it for a while.