[dba-SQLServer] Hardware Upgrade ?

Hi to all
 
We are in the process of upgrading to a SAN.   As part of this our SQL
Server is going to new server hardware as well.  My question is about
the best way to migrate data.  I have always had the impression that you
had to back up inside SQL and then use the backup file (.bak) in SQL for
a restore rather than backing up the .mdf and .ldf files.   Part of this
SAN is software that is supposed to do a low level copy from current
volumes to new volumes.  Once all data is migrated the new server will
be named the same as the old server and given the same IP address.  
That should prevent applications from going fits, I hope.  Any
suggestions on the best route to take or things to watch out for.  
 
Clay