I have got an 3com Etherlink III Isa (3com509b-TPO)in PnP-modus networkcard. I did a new install and the dialog to configure a network didn't show up. The previous redhat releases (5.2 and 6.0) did the job correctly during the installation procedure.
change component to installer
If the card is not autoprobed, then the network config screens will not show up. If your card is not getting probed correctly, then run the installer in expert mode and specify its parameters.