Can you download and use MSN Messenger on a MAC?

Yes. See the Related Link for "Microsoft.com: MSN messenger for a Mac" to the bottom for the answer. Or you can just go to mail, click on add account then scroll to the bottom and press alternative account you then enter the URL for MSN messenger and click find. If the URL is correct, it will ask you to sign in. You could also pin a link directly from the internet onto your task bar.