New to exchange server 2003. I'm new to exchange server. I have server already running ms Exchange

Question

I'm new to exchange server. I have server already running ms Exchange 2003 etrps. Etd. With windows server 2003 eptn. Etd. This server have losts of error coming on this VERITAS backup also not working cant take proper backup. I'm installing new exchange server 2003 in other machine I would like to know how I can copy exiting user's mailboxes and public folders to newly installed exchange server. Although existing one cant working properly cant take backup please advise.
My new exchange server with in the organization what exactly I need I want to bring up newly installed exchange with same name as old server (server-mail) and want to discontinued old server use. Please advise the entire step how I can brink up new server with same name and how can I move all mail boxes and all other public folders without any difficulty. Really appreciate you response