overall, i get the feeling that, with careful storage, your media is going 
to outlive your software
so you're going to have to set up long-term maintenance programs for any 
archive: copy & convert with every software/media update
just like we got everything off those big ugly floppy disks and moved them 
to smaller disks, then cds, we're eventually have to switch to blue laser 
disks
also surprised none of our british friends have mentioned the AHDS, the Arts 
& Humanities Data Service & their various guides to "good practice" on 
digital archives
check 'em out at:
http://www.ahds.ac.uk/