I had it working for a while, and it was working after installing the ATI driver. Im using dual monitors also.
I get a message “Failed to activate desktop effects…Check your X config”
xorg.conf
# /.../
# SaX generated X11 config file
# Created on: 2009-05-09T13:55:52+0100.
#
# Version: 8.1
# Contact: Marcus Schaefer <sax@suse.de>, 2005
# Contact: SaX-User list <https://lists.berlios.de/mailman/listinfo/sax-users>
#
# Automatically generated by [ISaX] (8.1)
# PLEASE DO NOT EDIT THIS FILE!
#
Section "Files"
FontPath "/usr/share/fonts/misc:unscaled"
FontPath "/usr/share/fonts/local"
FontPath "/usr/share/fonts/75dpi:unscaled"
FontPath "/usr/share/fonts/100dpi:unscaled"
FontPath "/usr/share/fonts/Type1"
FontPath "/usr/share/fonts/URW"
FontPath "/usr/share/fonts/Speedo"
FontPath "/usr/share/fonts/PEX"
FontPath "/usr/share/fonts/cyrillic"
FontPath "/usr/share/fonts/latin2/misc:unscaled"
FontPath "/usr/share/fonts/latin2/75dpi:unscaled"
FontPath "/usr/share/fonts/latin2/100dpi:unscaled"
FontPath "/usr/share/fonts/latin2/Type1"
FontPath "/usr/share/fonts/latin7/75dpi:unscaled"
FontPath "/usr/share/fonts/baekmuk:unscaled"
FontPath "/usr/share/fonts/japanese:unscaled"
FontPath "/usr/share/fonts/kwintv"
FontPath "/usr/share/fonts/truetype"
FontPath "/usr/share/fonts/uni:unscaled"
FontPath "/usr/share/fonts/CID"
FontPath "/usr/share/fonts/ucs/misc:unscaled"
FontPath "/usr/share/fonts/ucs/75dpi:unscaled"
FontPath "/usr/share/fonts/ucs/100dpi:unscaled"
FontPath "/usr/share/fonts/hellas/misc:unscaled"
FontPath "/usr/share/fonts/hellas/75dpi:unscaled"
FontPath "/usr/share/fonts/hellas/100dpi:unscaled"
FontPath "/usr/share/fonts/hellas/Type1"
FontPath "/usr/share/fonts/misc/sgi:unscaled"
FontPath "/usr/share/fonts/xtest"
FontPath "/opt/kde3/share/fonts"
InputDevices "/dev/gpmdata"
InputDevices "/dev/input/mice"
EndSection
Section "ServerFlags"
Option "AIGLX" "on"
Option "AllowMouseOpenFail" "on"
Option "IgnoreABI" "on"
Option "ZapWarning" "on"
EndSection
Section "Module"
Load "glx"
Load "extmod"
Load "freetype"
Load "dbe"
Load "dri"
EndSection
Section "InputDevice"
Driver "kbd"
Identifier "Keyboard[0]"
Option "Protocol" "Standard"
Option "XkbLayout" "gb"
Option "XkbModel" "microsoftpro"
Option "XkbRules" "xfree86"
EndSection
Section "InputDevice"
Driver "mouse"
Identifier "Mouse[1]"
Option "Buttons" "5"
Option "Device" "/dev/input/mice"
Option "InputFashion" "Mouse"
Option "Name" "Logitech;MX310"
Option "Protocol" "explorerps/2"
Option "Vendor" "Sysp"
Option "ZAxisMapping" "4 5"
EndSection
Section "Monitor"
Option "CalcAlgorithm" "XServerPool"
DisplaySize 376 301
HorizSync 30-82
Identifier "Monitor[0]"
ModelName "VIEWSONIC VX912"
Option "DPMS"
Option "PreferredMode" "1280x1024"
VendorName "VSC"
VertRefresh 43-85
UseModes "Modes[0]"
EndSection
Section "Modes"
Identifier "Modes[0]"
Modeline "1280x1024" 108 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
EndSection
Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1280x720" "1024x768" "1280x600" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1280x720" "1024x768" "1280x600" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1280x720" "1024x768" "1280x600" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1280x720" "1024x768" "1280x600" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection
Section "Device"
BoardName "RADEON X850 XT Platinum Edition (R480 5D4D)"
Driver "fglrx"
Identifier "Device[0]"
Option "SaXDualHead"
Option "XAANoOffscreenPixmaps" "true"
Option "Capabilities" "0x00000000"
Option "SaXDualMode" "Xinerama"
Option "ForceMonitors" "auto,crt1"
Option "SaXDualHSync" "30-82"
Option "SaXDualMonitorModel" "VIEWSONIC VX912"
Option "SaXDualVSync" "50-85"
Option "VRefresh2" "50-85"
Option "Mode2" "1280x1024,1280x960,1280x800,1152x864,1280x768,1280x720,1024x768,1280x600,1024x600,800x600,768x576,640x480"
Option "FSAAScale" "0"
Option "FSAAEnable" "off"
Option "VideoOverlay" "on"
Option "SaXDualMonitorVendor" "VSC"
Option "HSync2" "30-82"
Option "SaXDualResolution" "1280x1024"
Option "DesktopSetup" "Horizontal,Reverse"
Option "SaXDualOrientation" "RightOf"
Screen 0
VendorName "ATI"
EndSection
Section "ServerLayout"
Identifier "Layout[all]"
InputDevice "Keyboard[0]" "CoreKeyboard"
InputDevice "Mouse[1]" "CorePointer"
Option "Clone" "off"
Option "Xinerama" "off"
Screen "Screen[0]"
EndSection
Section "DRI"
Group "video"
Mode 0660
EndSection
Section "Extensions"
EndSection
fglrxinfo
display: :0.0 screen: 0
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: RADEON X850 XT Platinum Edition
OpenGL version string: 2.1.8494 Release
Also have one more issue, unrelated? but using vlc for videos, and opengl renderer, the video quality is really low -almost blocky but its more of a strange chess board type pattern. It renders fine with X11 video output, but for HD stuff thats quite slow
thanks
Mark