[CentOS] I've lost control of Gnome

I tried out KDE for a while, but eventually found that it was not to my liking. I've switched back to Gnome, but it seems to me that options I used to have in the panel aren't available anymore. I'm not totally sure, but isn't there supposed to be some sort of Gnome (Nautilus?) control center? A place where I can adjust the themes, screen savers, and that sort of thing? I was sure it was there, and now I can't find it, and I'm lost about exactly which problem I should be fixing. Should there be a theme manager? If so where? I came across a theme switcher application, installed the RPM, and I can't find it in the applications menu either.

Is Gnome upset with me for having been with KDE behind it's back?

Dave