Well, the guys at Netgear recommend keeping a 2nd ReadyNAS Pro off-site somewhere!
Actually, I would recommend a decent external USB enclosure that supports SATA and PATA/IDE drives, as well as USB, Firewire & eSATA interfaces. This way, you can use the enclosure to use both newer and older drive types, as well as connect to different computers/devices.
I can't give you any recommendations, but something like this has most of the features:http://www.usb-ware.com/usb-2-enclosure ... stu35k.htm
My main feature would be support for both SATA & IDE/PATA drives with USB. Firewire and eSATA are not needed by me, as I do not have any devices that support either technology.
Check the HCL first, though:http://www.readynas.com/?page_id=89