1. have you got kde and gnome both on your system? if so, you can only switch between them after booting the machine - from one of the login managers (gdm,kdm,xdm) - which will list which one you want. so, install kde from the rh cd's, if you already havent.
2. what card do you have? look up the relevant lines from "lspci", which will give you the name. write back here what it is (if you dont already know). also, see what "ifconfig" gives you. if it shows you anything apart from "lo" , then the cards' up. write back here what it says if it is.