[CentOS] Copy OS live to different hardware

Hello,

I've got some CentOS 5.3 servers that I want to clone to a backup server,
possibly a VM machine.  I want this to be done while the server is up, and
keep it synced at least once a day.

I've done this already by using RSYNC, but here's the twist: the backup
machine could be different hardware, and needs to have a different IP address
(so they don't conflict).

My question: exactly what files should I exclude, so that I copy everything
-except- what pertains to the ethernet card(s), and hard drive mounts.  I know
of at least:

/etc/fstab
/etc/sysconfig/network-scripts/*
/var/run
/proc

But what else?  The original servers may have software raid, so those files
can't be copied either.

Bob