well, i didnt thought too much about it, but, if the backups are on dvd or
another hard drive, you can get back your data if:
1.- install virtual pc or vmware
2.- install the rc1 into a virtual machine, same edition from where you made
the backup (ultimate)
3.- ensure the virtual machine sees the backup media and try to restore the
backup into the virtual machine
4.- move your data from the virtual machine to your real machine, either by
net, additions or whatever you want to use :-)

as it is timebombed, try to set the virtual machine date to before june and
cut out its internet connection, that (probably) will give you enough room
and time to do your things

on a sidenote, i didnt tried to do this, but if your backup media gets seen
to the virtual machine, it should work flawlessly, i think