Another problem: I've never heard of any reasonably usable networked FS for Windows besides SMB/CIFS. Do you know more than me? If you do, can you name a few large sites that have been successfully running it so my (ficticious) PHB would feel safe to give the go-ahead to implement it?
American Universities run Kerberos, LDAP and AFS for their authentication/user directory/file storage. It supports load balancing, high availability, ACL's and multiple other buzzwords. There are clients for various OS's including Windows. It's faster than your average network file system, because it uses the local file system as a disk cache. (On the flipside, I've personally never managed to get it working, but you don't need to tell the PHB that :)