a chi potesse interessare:
il mio hardware scheda video nvidia fx5900xt con 2 video lcd (lg 1710b).... posto la configurazione funzionante con xinerama di XF86Config...

# /.../
# SaX generated XFree86 config file
# Created on: 2004-07-09T22:12:26+0200.
#
# Version: 4.8
# Contact: Marcus Schaefer <sax@suse.de>, 2002
#
# Automatically generated by [ISaX] (4.8)
# PLEASE DO NOT EDIT THIS FILE!
#
Section "Files"
FontPath "/usr/X11R6/lib/X11/fonts/misc:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/local"
FontPath "/usr/X11R6/lib/X11/fonts/75dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/Type1"
FontPath "/usr/X11R6/lib/X11/fonts/URW"
FontPath "/usr/X11R6/lib/X11/fonts/Speedo"
FontPath "/usr/X11R6/lib/X11/fonts/PEX"
FontPath "/usr/X11R6/lib/X11/fonts/cyrillic"
FontPath "/usr/X11R6/lib/X11/fonts/latin2/misc:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/latin2/75dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/latin2/100dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/latin2/Type1"
FontPath "/usr/X11R6/lib/X11/fonts/latin7/75dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/baekmuk:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/japanese:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/kwintv"
FontPath "/usr/X11R6/lib/X11/fonts/truetype"
FontPath "/usr/X11R6/lib/X11/fonts/uni:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/CID"
FontPath "/usr/X11R6/lib/X11/fonts/ucs/misc:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/ucs/75dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/ucs/100dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/hellas/misc:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/hellas/75dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/hellas/100dpi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/hellas/Type1"
FontPath "/usr/X11R6/lib/X11/fonts/misc/sgi:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/xtest"
FontPath "/opt/kde3/share/fonts"
InputDevices "/dev/ttyS0"
InputDevices "/dev/ttyS1"
InputDevices "/dev/ttyS2"
InputDevices "/dev/ttyS3"
InputDevices "/dev/ttyS4"
InputDevices "/dev/ttyS5"
InputDevices "/dev/ttyS6"
InputDevices "/dev/ttyS7"
InputDevices "/dev/ttyS8"
InputDevices "/dev/psaux"
InputDevices "/dev/logibm"
InputDevices "/dev/sunmouse"
InputDevices "/dev/atibm"
InputDevices "/dev/amigamouse"
InputDevices "/dev/atarimouse"
InputDevices "/dev/inportbm"
InputDevices "/dev/gpmdata"
InputDevices "/dev/mouse"
InputDevices "/dev/usbmouse"
InputDevices "/dev/adbmouse"
InputDevices "/dev/input/mice"
InputDevices "/dev/input/event0"
InputDevices "/dev/pointer0"
InputDevices "/dev/pointer1"
InputDevices "/dev/pointer2"
InputDevices "/dev/pointer3"
EndSection

Section "ServerFlags"
Option "AllowMouseOpenFail"
Option "RandR" "on"
EndSection

Section "Module"
Load "v4l"
Load "extmod"
Load "type1"
Load "freetype"
Load "dbe"
Load "speedo"
Load "glx"
EndSection

Section "InputDevice"
Driver "Keyboard"
Identifier "Keyboard[0]"
Option "Protocol" "Standard"
Option "XkbLayout" "it"
Option "XkbModel" "pc102"
Option "XkbRules" "xfree86"
EndSection

Section "InputDevice"
Driver "mouse"
Identifier "Mouse[1]"
Option "Buttons" "5"
Option "Device" "/dev/input/mice"
Option "Name" "Autodetection"
Option "Protocol" "explorerps/2"
Option "Vendor" "Sysp"
Option "ZAxisMapping" "4 5"
EndSection

Section "Device"
Identifier "NVIDIA"
Driver "nvidia"
EndSection

Section "Monitor"
Identifier "LG"
HorizSync 30-80
VertRefresh 75 #56
Option "DPMS"
EndSection

Section "Screen"
Identifier "Screen0"
Device "NVIDIA"
Monitor "LG"
DefaultDepth 24

Option "NvAGP" "1"
Option "TwinView" "true"
Option "SecondMonitorHorizSync" "30.0-60.0"
Option "SecondMonitorVertRefresh" "50.0-75.0"
Option "MetaModes" "1024x768, 1024x768; 1024x768, 1024x768;"
Option "TwinViewOrientation" "RightOf"
Option "Xinerama" "on"

SubSection "Display"
Depth 1
Modes "1024x768"
EndSubSection
SubSection "Display"
Depth 4
Modes "1024x768"
EndSubSection
SubSection "Display"
Depth 8
Modes "1024x768"
EndSubSection
SubSection "Display"
Depth 15
Modes "1024x768"
EndSubSection
SubSection "Display"
Depth 16
Modes "1024x768"
EndSubSection
SubSection "Display"
Depth 24
Modes "1024x768"
ViewPort 0 0
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Layout[all]"
InputDevice "Keyboard[0]" "CoreKeyboard"
InputDevice "Mouse[1]" "CorePointer"

# Identifier "Default Layout"
Screen 0 "Screen0" 0 0
# InputDevice "Generic Keyboard"
# InputDevice "Configured Mouse"
# InputDevice "Generic Mouse"
EndSection

#Section "DRI"
# Mode 0666
#EndSectiowhi
### END DEBCONF SECTION