I would like to come up with a way to provide a full backup computer to my customers (offline, process control application). Currently doing this with WinXP and a hot-swap RAID-1 enclosure. If anything in computer1 dies, can quickly move the cables and the drive over to computer2, boot up and keep running. Now moving to Windows 7, more strict activation issues. Getting a separate windows license for each computer is not a problem, but how to either change the license key easily after the swap, or avoid activation altogether? Typical system is offline, possibly abroad and would like to make the failover as easy as possibly for customers. Currently using OEM license but open to other ideas. Have tested with Retail copy of Windows 7 Pro and get 3-days to activate after moving to backup computer, same as OEM. Would volume licensing help me here? Other ideas?