This is what you will have to do.
1. Enable the nfs server.
2. create iso images of each cd on your hard disk. You will need 5 GB to to do that
3. mount these images on the hard disk using loop device under your nfs exported directory. to a client it will look like you have 7 cd drives on your machine
4. To do the above I suggest you download and read the excellent "debian reference manual" available at www.debian.org