For handling the dual LCDs with the X1800XT in dual-head, below is the xorg.conf used in my specific configuration on Fedora Core 5. However, this configuration will change quite a bit through the trial.
Section "ServerLayout" Identifier "Default Layout" Screen 0 "aticonfig-Screen[0]" 0 0 Screen "aticonfig-Screen[1]" RightOf "aticonfig-Screen[0]" InputDevice "Mouse0" "CorePointer" InputDevice "Keyboard0" "CoreKeyboard" EndSection Section "Files" RgbPath "/usr/X11R6/lib/X11/rgb" FontPath "unix/:7100" EndSection Section "Module" Load "dbe" Load "extmod" Load "fbdevhw" Load "glx" Load "record" Load "freetype" Load "type1" Load "dri" EndSection Section "InputDevice" Identifier "Keyboard0" Driver "kbd" Option "XkbModel" "pc105" Option "XkbLayout" "us" EndSection Section "InputDevice" Identifier "Mouse0" Driver "mouse" Option "Protocol" "IMPS/2" Option "Device" "/dev/input/mice" Option "ZAxisMapping" "4 5" Option "Emulate3Buttons" "yes" EndSection Section "Monitor" Identifier "aticonfig-Monitor[0]" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" EndSection Section "Monitor" Identifier "aticonfig-Monitor[1]" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" EndSection Section "Device" Identifier "aticonfig-Device[0]" Driver "fglrx" BusID "PCI:1:0:0" EndSection Section "Device" Identifier "aticonfig-Device[1]" Driver "fglrx" BusID "PCI:1:0:0" Screen 1 EndSection Section "Screen" Identifier "aticonfig-Screen[0]" Device "aticonfig-Device[0]" Monitor "aticonfig-Monitor[0]" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "aticonfig-Screen[1]" Device "aticonfig-Device[1]" Monitor "aticonfig-Monitor[1]" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "DRI" Group 0 Mode 0666 EndSection
