got a pic of the inside of your case? would help
but there is always room for drives .resting on the bottom, where the floppy lives, sitting in the cd rom bays hanging from the roof on wire and covered using bubble rap
do u need 4 drives? get 2 huge ones or even one small one to boot from and one huge one to do with what ya like.
how about an external usb/firewire drive ..all sorts u can do and im sure they will fit just nudge em in ..
what other stuff do u have in the pc in the way of dvd's etc