Proprietary format for you data is only a problem if you don't have the viewer. If you make a habit of getting a viewer application on the disk along with the data you are probably GTG. Yes there could be a problem finding an older OS version that is capable of runnig your viewer app. You could go with something like a minimal linux like Knoppix and burning a boot image on along with appropriate viewers. Takes up some of your data space but not all of it and then you have a bootable CD with viewer apps for all stored data and all you need is a x86 pc that can boot from the CD. Makes the backup process a bit heavier but it can be scripted to lay down the knoppix + viewers on each CD that is submitted for use as a backup media. Not too hard with a linux based environment. In a windows environment where your backup is some proprietary software instead of the simple shell script then this sort of approach might be a bit more difficult. Never seen a "minimal" win2K bootable CD with any room left over for data.