[CentOS] KDE as default, and looking up CentOS on the web.

This should be simple, but I can't find it on the web: How do I make KDE my default environment? Every time I reboot it goes back to Gnome unless I specifically change the environment before logging in.

And while I'm at it, why is it I never find any information about CentOS on the net? I look up "CentOS KDE default" or something like that, and I get more about things like Mandrake or Fedora or any other distro than I do about CentOS. I know that CentOS is supposed to be on the same level as Fedora Core 3 and Red Hat Enterprise 8 or 9... but still, why is it that no one even seems to mention CentOS? It's like this big but invisible community of users.

Dave