no xorg.conf on debian5.02

Hi,
I was suprised by the xorg on debian 5.02 (the latest release). There is no file xorg.conf in /etc/X11.
I want to change the resolution for the screen to 1280x1024 , 1024x768   and the default Keyboard ,  where to do ii.
In another word  from where the xorg takes the parameter for the X ( keyboard, mouse, display, resolution .....)

thanks for help
best regards
bela