Linux question: mounting a Windows FS to RHEL server using Samba

We're trying to CIFS mount a Windows file system to our RHEL5 server using Samba. It is easy enough to do that, and we have done it a few times, read-only (on purpose). Now we want to mount a Win FS as read-write, and our Linux admin (who is pretty green) cannot get it to take... it is read-only no matter what he tries. We've got Red Hat Enterprise support, but so far they've been no help. Any ideas?

Missing Chuck Dombek's vast experience right about now!!

-Jay B