It's possible to have a GUI system without Network Manager. I just built (am building) an xbmc system and used CentOS 6 for it. It has gnome running with xbmc on top and I have no Network Mana... [by TrevorH]
I have installed F17 with Gnome 3 desktop and all updates. My desktop sits behind a router running dd-wrt which handles all connections to my isp and provides a static ip to my desktop. I decided to remove network manager and simply use system-config-network-gui to setup my connection. My desktop config isn't that complicated... it's just dhcp with everything handled at the router.
I have a fresh install of 12.10 on my HTPC running XBMC. I'm running into an issue though which is causing some bigger issues. When the system boots up and loads into the default profile, the network takes around an additional 30 seconds before it comes online. This didn't happen prior to the fresh install - it was pretty much instant and ready as soon as the system was up.