Si no tenemos una tarjeta gráfica con doble  salida (VGA y DVi) pero 
tenemos 2 tarjetas PCI, o una AGP y una PCI podemos usar las 2 salidas 
VGA y conectar sendos monitores.  
 

 Mis tarjetas son  (según lspci) : la 1º  una <b>nVidia GeForce4 MX 
440 AGP 8x</b> y la 2º una <b> S3 Inc. ViRGE/GX2</b>.
   
   La tarjeta nVidia va conectada a un monitor TFT Arnos Instruments 
F-417 de 1280x1024 puntos de resolución y la S3 a un CRT LG Studioworks 
520Si de 1024x768.


<b>xorg.conf-dos-monitores-dos-tarjetas</b>

#######  Files y Modules ########
	
Section "Files"
	FontPath "/usr/share/X11/fonts/misc"
	FontPath "/usr/share/X11/fonts/cyrillic"
	FontPath "/usr/share/X11/fonts/100dpi/:unscaled"
	FontPath "/usr/share/X11/fonts/75dpi/:unscaled"
	FontPath "/usr/share/X11/fonts/Type1"
	FontPath "/usr/share/X11/fonts/100dpi"
	FontPath "/usr/share/X11/fonts/75dpi"
	FontPath "/usr/share/fonts/X11/misc"
	FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
	Load "i2c"
	Load "bitmap"
	Load "ddc"
	Load "extmod"
	Load "freetype"
	Load "glx"
	Load "int10"
	Load "type1"
	Load "vbe"
	Load "v4l"
	Load "dbe"
EndSection

###  Seccion Dispositivos de entrada ###

# Teclado
Section "InputDevice"
	Identifier "Generic Keyboard"
	Driver "kbd"
	Option "CoreKeyboard"
	Option "XkbRules" "xorg"
	Option "XkbModel" "pc105"
	Option "XkbLayout" "es"
EndSection

# Raton
Section "InputDevice"
	Identifier "Configured Mouse"
	Driver "mouse"
	Option "CorePointer"
	Option "Device" "/dev/input/mice"
	Option "Protocol" "ExplorerPS/2"
	Option "ZAxisMapping" "4 5"
	Option "Emulate3Buttons" "true"
EndSection


###### Seccion Monitor #####

# Monitor izquierdo TFT
Section "Monitor"
	Identifier "Monitor0"
	VendorName "Unknown"
	ModelName "Arnos Instruments F-417"
	Option "DPMS"
EndSection

#Monitor derecho CRT
Section "Monitor"
	Identifier "Monitor1"
	VendorName "Unknown"
	ModelName "lg"
	Option "dpms"
EndSection

###### Seccion Device ######

# Tarjeta nVidia
Section "Device"
	Identifier "Videocard0"
	Driver "nvidia"
	Option "AddARGBVisuals" "True"
	Option "NoLogo" "True"
	VendorName "NVIDIA Corporation"
	BoardName "GeForce FX 5200"
	BusID "PCI:1:0:0"
EndSection

# Tarjeta S3 ViRGE
Section "Device"
	Identifier "s3"
	Driver "s3virge"
	VendorName "s3 inc"
	BoardName "86c325"
	BusID "PCI:0:11:0"
EndSection

###### Seccion Screen ######

Section "Screen"
	Identifier "Screen nvidia0"
	Device "Videocard0"
	Monitor "Monitor0"
	DefaultDepth 16
		SubSection "Display"
			Viewport 0 0
			Depth 24
			Modes "1024x768"
		EndSubSection
EndSection

Section "Screen"
	Identifier "Screen s3"
	Device "s3"
	Monitor "Monitor1"
	DefaultDepth 16
		SubSection "Display"
			Viewport 0 0
			Depth 24
			Modes "1024x768"
		EndSubSection
EndSection


# ======ServerLayout=========

Section "Extensions"
	Option "RENDER" "Enable"
EndSection

Section "ServerLayout"
	Identifier "BothTwinView"
	Screen "Screen nvidia0"
	Screen "Screen s3"  RightOf "Screen nvidia0"
	Option "Xinerama" 
	InputDevice "Configured Mouse" "CorePointer"
	InputDevice "Generic Keyboard" "CoreKeyboard"
EndSection


Presenta alguna inestabilidad a la hora de arrancar, a veces hay que 
resetear y repetir el arranque con recovery mode ( cp 
xorg.conf-dos-monitores-dos-tarjetas xrog.conf y luego exit ). 
Tambien observo que se congela el sistema al cerrar la sesion X. No 
vuelve al gdm, se queda la pantalla en negro y no responde a nada salvo 
el botón de reset.
Por lo demás, una vez que arranca funciona con las dos pantallas sin 
problema.