This is my /etc/X11/xorg.conf. Thank you to Mark's Wiki!

# Xorg configuration created by system-config-display

Section "ServerLayout"
        Identifier     "ServerLayout"
        Screen       1  "External Screen"
        Screen       0  "Internal Screen"
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
EndSection


Section "ServerFlags"
        Option "PM" "off"
        Option "DPMS" "off"
        Option "Xinerama" "0"
EndSection


Section "Files"

# RgbPath is the location of the RGB database.  Note, this is the name of the 
# file minus the extension (like ".txt" or ".db").  There is normally
# no need to change the default.
# Multiple FontPath entries are allowed (they are concatenated together)
# By default, Red Hat 6.0 and later now use a font server independent of
# the X server to render fonts.
   RgbPath      "/usr/share/X11/rgb"
   FontPath    "/usr/share/fonts/misc:unscaled"
   FontPath    "/usr/share/fonts/Type1"
   FontPath    "/usr/share/fonts/TTF"
   FontPath    "/usr/share/fonts/75dpi:unscaled"
   FontPath    "/usr/share/fonts/100dpi:unscaled"
EndSection

Section "Module"
        Load  "record"
        Load  "extmod"
        Load  "dbe"
        Load  "dri"
        Load  "glx"
        Load  "xtrap"
        Load  "freetype"
        Load  "type1"
        Load  "speedo"
        Load  "radeon"
        Load   "drm"
EndSection

Section "DRI"
        Mode         0666
EndSection

Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "keyboard"
        Option      "XkbModel" "pc105"
        Option      "XkbLayout" "us"
        Option      "XkbVariant" "nodeadkeys"
EndSection

Section "InputDevice"
        Identifier  "Mouse0"
        Driver      "mouse"
        Option      "Protocol" "Auto"
        Option      "Device" "/dev/input/mice"
        Option      "ZAxisMapping" "4 5"
        Option      "Emulate3Buttons" "yes"
EndSection

Section "Monitor"
        Identifier   "Monitor1"
        VendorName   "IBM"
        ModelName    "X31 TFT Screen"
        HorizSync    31.5 - 48.5
        VertRefresh  40.0 - 70.0
#        Option       "DPMS"
        DisplaySize  243.84 182.88
EndSection

Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Sharp"
        ModelName    "LL-191A-B"
        HorizSync    31.5 - 79.0
        VertRefresh  60.0 - 75.0
        DisplaySize  386.4 289.8
#        Option       "DPMS"
EndSection


Section "Device"
        Identifier      "Card0"
        Driver          "radeon"
        BusID           "PCI:1:0:0"
        Option          "AGPMode" "4"
#        Option          "AGPSize" "16"         # default: 8
        Option          "AGPFastWrite" "false"  # MUST BE FALSE!
        Option          "SWcursor" "true"           # MUST BE TRUE!
#        Option          "RingSize" "4"
#        Option          "BufferSize" "2"
        Option          "EnablePageFlip" "false"          # necessary?
        Option          "EnableDepthMoves" "false"      # MUST BE FALSE!
        Option          "RenderAccel" "false"
        Option          "AccelMethod" "XAA"     # or XAA, EXA
        Option          "DDCMode"
        Option          "SubPixelOrder" "NONE"
        Option          "ColorTiling" "false"   # MUST BE FALSE?
        Option          "DynamicClocks" "true"
        Option          "bioshotkeys"   "True"
        Option          "XAANoOffscreenPixmaps" "true"
EndSection


Section "Screen"
        Identifier "External Screen"
        Device     "Card0"
        Monitor    "Monitor0"
        DefaultDepth    24
        SubSection "Display"
                Viewport   0 0
                Depth     16
                Modes    "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
        EndSubSection
EndSection


Section "Screen"
        Identifier "Internal Screen"
        Device     "Card0"
        Monitor    "Monitor1"
        DefaultDepth    24
        SubSection "Display"
                Viewport   0 0
                Depth     16
                Modes    "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1024x768" "800x600" "640x480"
        EndSubSection
EndSection