I've been struggling with my dual monitor setup in Mandriva 2008.0 for 2 solid days now and a lot of coffee support
I followed the advice on various posts from several linux websites and so far I got big-desktop to work and I can drag windows between them which is good, but with the following problems:

I only have 2 resolution options in ATI Catalyst Control Center: 2560x1024 and 1024x480. Currently I have it set on 2560x1024 but the monitors dont support a high refresh rate at this resolution so they have a lot of flicker at 60Hz. The 1024x480 resolutionis way too low for practical use. The monitors are both AOpen 17" with 1024x768@85Hz as my preferred resolution. My card is an ATI Radeon 9600.

When I run fglrxinfo I get the following:

Code:
[johan@localhost ~]$ fglrxinfo
display: :0.0  screen: 0
OpenGL vendor string: Mesa project: www.mesa3d.org
OpenGL renderer string: Mesa GLX Indirect
OpenGL version string: 1.4 (2.1 Mesa 7.0.1)
The xorg.conf file is as follows:
Code:
# File generated by XFdrake (rev 230776)
# **********************************************************************
# Refer to the xorg.conf man page for details about the format of
# this file.
# **********************************************************************

Section "ServerLayout"
	Identifier     "layout1"
	Screen      0  "aticonfig-Screen[0]" 0 0
	InputDevice    "Keyboard1" "CoreKeyboard"
	InputDevice    "Mouse1" "CorePointer"
	InputDevice    "Mouse2" "SendCoreEvents"
EndSection

Section "Files"
EndSection

Section "Module"
	Load  "dbe" # Double-Buffering Extension
	Load  "v4l" # Video for Linux
	Load  "extmod"
	Load  "type1"
	Load  "freetype"
	Load  "glx" # 3D layer
	Load  "dri" # direct rendering
EndSection

Section "ServerFlags"

    #DontZap # disable <Ctrl><Alt><BS> (server abort)
    #DontZoom # disable <Ctrl><Alt><KP_+>/<KP_-> (resolution switching)
 # allows the server to start up even if the mouse does not work
	Option	    "allowmouseopenfail"
EndSection

Section "InputDevice"
	Identifier  "Keyboard1"
	Driver      "kbd"
	Option	    "XkbModel" "pc105"
	Option	    "XkbLayout" "us(alt-intl)"
	Option	    "XkbOptions" "compose:rwin"
EndSection

Section "InputDevice"
	Identifier  "Mouse1"
	Driver      "mouse"
	Option	    "Protocol" "ExplorerPS/2"
	Option	    "Device" "/dev/mouse"
EndSection

Section "InputDevice"
	Identifier  "Mouse2"
	Driver      "evdev"
	Option	    "bustype" "0x0003"
	Option	    "product" "0x0039"
	Option	    "relBits" "+0+1+2"
	Option	    "HWheelRelativeAxisButtons" "7 6"
	Option	    "vendor" "0x0458"
EndSection

Section "Monitor"

    # TV fullscreen mode or DVD fullscreen output.
    # 768x576 @ 79 Hz, 50 kHz hsync
	Identifier   "monitor1"
	VendorName   "Plug'n Play"
	ModelName    "VM7V"
	HorizSync    30.0 - 72.0
	VertRefresh  50.0 - 160.0
	ModeLine     "768x576" 50.0 768 832 846 1000 576 590 595 630
	ModeLine     "768x576" 63.1 768 800 960 1024 576 578 590 616
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  "device1"
	Driver      "fglrx"
	VendorName  "ATI Technologies Inc"
	BoardName   "ATI Radeon 9500 - X850"
	Option	    "DPMS"
	Option	    "XaaNoOffscreenPixmaps" "1"
	Option	    "DesktopSetup" "horizontal"
	Option	    "Mode2" "1024x768" #Resolution for second monitor
	Option	    "HSync2" "65"
	Option	    "VRefresh2" "60"
	Option	    "OverlayOnCRTC2" "1"
	Option	    "Capabilities" "0x00000800"
	Option	    "PairModes" "0x0+0x0"
	Option	    "EnableMonitor" "crt1,crt2"
EndSection

Section "Device"
	Identifier  "aticonfig-Device[0]"
	Driver      "fglrx"
	Option	    "ATIFGLEXTENSION" "Keyboard1"
	BusID       "PCI:1:0:0"
EndSection

Section "Device"
	Identifier  "aticonfig-Device[1]"
	Driver      "fglrx"
	Option	    "HSync2" "65"
	Option	    "VRefresh2" "60"
	BusID       "PCI:1:0:0"
	Screen      1
EndSection

Section "Screen"
	Identifier "screen1"
	Device     "device1"
	Monitor    "monitor1"
	DefaultDepth     16
	SubSection "Display"
		Depth     8
		Modes    "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
	EndSubSection
	SubSection "Display"
		Depth     15
		Modes    "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
	EndSubSection
	SubSection "Display"
		Depth     16
		Modes    "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
	EndSubSection
	SubSection "Display"
		Depth     24
		Modes    "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
	EndSubSection
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 "Extensions"
	Option	    "Composite"
EndSection
I tried several options to get the resolution/refresh rate issue sorted but no luck so far. Any help would be really appreciated!

Johan