I do not think most distros will allow you to install from an ISO image over a network. From an image on the harddrive, yes. Over the network, yes. But I don't think you can do both without a little work.
Presuming your file server is a Linux machine, and you are on good terms with your admin, what you could do, of course, is trick it into thinking that it is just a normal network install. If you mount the ISO image on the server and then share that mountpoint with nfs/smbfs then you should be able to do a normal network install. Beware, however, that when installing over a network like this it is normally expected that all the files from all the CDs are present and shared in the same place, so with the above method you will only have access to the first CD of a set unless you do something sneaky like mount the other ISOs aswell, symlink the whole lot somewhere else and share that directory.
Hope this helps.