If you do go the multiple storage media route, too, remember to keep checking each for signs of degredation. It's fairly quick and easy to do a SHA1 hash run over all the files on a drive and compare the results, as well as storing the list of hashes itself in multiple locations. That way, even if you get read errors at some point, you can determine which copy is "good".
On Windows, can this be done on the command line without downloading a checksum utility program? How then should we store the list of hashes? Will there be any difference between NTFS and FAT32 systems?