I prefer to use http and yum. If you can setup your machine that contains the installation tress with apache, then just modify your /etc/yum.conf I find it easier this way because if i want to add my own rpms, i simply rebuild the hdrs on the http server.
I prefer yum too actually.
You don't even need to set up apache, because you can use file:// URLs in yum.conf as well as http:// URLs (at least that's what "man yum.conf" says - I haven't tried it myself). This will only work if your NFS server is exporting a full tree though, not just the ISO images.
Paul.