Thanks for replying!
Doing everything as root, here's what happened.
I cd'd into the /usr/X11R6/bin directory and typed xf86config. It said the command wasn't found. So I typed the whole path /usr/X11R6/bin/xf86config. This time it did work. After I had configured everything, I rebooted.
Then I logged in as root, cd'd into the /usr/X11R6/bin directory and typed "startx". Once again, the command wasn't found. So I typed /usr/X11R6/bin/startx. And it gave me several error messages saying that neither "xauth" nor "xinit" were found. I checked the directory - both binaries were there. Lastly I tried typing "sh startx", but I got the same result.
Somehow I have a weird feeling that something is missing...
Maybe I should reinstall X ?
What do you say?