David,
I backup to the separate HD nightly (daily, weekly and monthly retained), then every few days or once week off-site to a server at another datacenter. I could have used the datacenter's backup solution but this is free for me and I have the bandwidth to spare (backing up between the 2 servers from different datacenters). Just make sure you use SSH2 for transfers off-site. So if there is an earthquake/fire/etc at a datacenter I'm still ok.
-vissa