What do you need to do to get Microsoft Exchange 2007 backed up with Backup Exec?
Support for Exchange 2007 was introduced with Backup Exec 11d build 7170, so if you're running a previous version you need to upgrade first.
Your Backup Exec media server must be running on a Windows Server 2003 machine – if it's running on a Windows 2000 server it won't work.
If your Backup Exec media server is running on a 32 bit version of Windows Server 2003, you must install the 32 bit Exchange Tools on the media server.
Your media server needs to have Microsoft Exchange Server MAPI Client and Collaboration Data Objects (MAPI/CDO) installed, which must be version 6.05.7888 or later.
If you wish to do mailbox backups, there are further configuration steps required, which are documented at http://seer.entsupport.symantec.com/docs/288777.htm