rsync over nfs or rsync protocol

[Jason C. Wells]

I am looking into finally setting up a backup solution that's a little 
more sophisticated than a bunch of DVD-RWs.  I have two servers.  I'd 
like to make each a backup server for the other.  I'm considering using 
rsync.

Is rsync a good choice for a backup tool?
Should I use the rsyncd or should I use NFS?  I'm using 100 mbps ethernet.
What's the better solution I haven't considered?

Thanks,
Jason