well - as you know a bit about pc's etc and your putting in a new mobo anyway why not get ur self a new Case plenty out there that can take 3+cd/dvd roms and a load of hjard drives.
its what id do if i was u far easier that farting around with what u have now and as u said u want it for expanibility, ur stuck now so think how u will be in the future..
have a look at
http://www.overclockers.co.uk/acatal...Cases_128.html
btw: as ur upgraidng from an old mobo that had isa slots - do u have a new PSU? if ur getting an AMD or Intel (sorry didnt look to see what cpu ur mobo takes) and a load of drives u will need a more powerful PSU maybe than ur current one ..