I want to build a dedicated MythTV box using CentOS5. I need a lightweight desktop environment, something extremely simple that does not use much memory. Gnome and KDE use way too much memory and are too complex for what I want to do. The system will login automatically to a certain account after booting up. After the automatic login, it will start immediately the MythTV frontend full-screen. If the frontend dies, the desktop needs to logout / log back in automatically. No other application will run on this machine, only mythfrontend. There will only be one account. Think of it as a single-purpose appliance, not a regular computer. Whatever I use as the desktop environment, it needs to be pretty standard - either included in the distribution proper, or in one of the major repositories. It must be very trivial to enable, with no hacking required to the OS. It must play well with mythfrontend, I don't need any compatibility issues. It must be a stable, reputable software.
Which desktop environment would you recommend based on the requirements?