Used win 7 and got resolution 1280x1024 and when i installed Ubuntu 11.04 got resolution of 1152x864(made that possible by changing from the advanced option in the nvidia xorg file)went to system settings and got 'monitor unknown'.Using a nvidia 8400GS and using 173 version of driver.

xrandr o/p:

xrandr: Failed to get size of gamma for output default

Screen 0: minimum 320 x 240, current 1152 x 864, maximum 1152 x 864

default connected 1152x864+0+0 0mm x 0mm

   1024x768       50.0     60.0  

   800x600        51.0     52.0     53.0  

   680x384        54.0     55.0  

   640x480        56.0  

   512x384        57.0  

   400x300        58.0  

   320x240        59.0  

   1152x864       60.0* 

xorg o/p:

# nvidia-settings: X configuration file generated by nvidia-settings

# nvidia-settings:  version 270.29  (buildd@roseapple)  Fri Feb 25 14:43:24 UTC 2011



Section "ServerLayout"

    Identifier     "Layout0"

    Screen      0  "Screen0" 0 0

    InputDevice    "Keyboard0" "CoreKeyboard"

    InputDevice    "Mouse0" "CorePointer"

    Option         "Xinerama" "0"

EndSection



Section "Files"

EndSection



Section "InputDevice"

    # generated from default

    Identifier     "Mouse0"

    Driver         "mouse"

    Option         "Protocol" "auto"

    Option         "Device" "/dev/psaux"

    Option         "Emulate3Buttons" "no"

    Option         "ZAxisMapping" "4 5"

EndSection



Section "InputDevice"

    # generated from default

    Identifier     "Keyboard0"

    Driver         "kbd"

EndSection



Section "Monitor"

    # HorizSync source: builtin, VertRefresh source: builtin

    Identifier     "Monitor0"

    VendorName     "Unknown"

    ModelName      "CRT-1"

    HorizSync       28.0 - 55.0

    VertRefresh     43.0 - 72.0

    Option         "DPMS"

EndSection



Section "Device"

    Identifier     "Device0"

    Driver         "nvidia"

    VendorName     "NVIDIA Corporation"

    BoardName      "GeForce 8400 GS"

EndSection



Section "Screen"

    Identifier     "Screen0"

    Device         "Device0"

    Monitor        "Monitor0"

    DefaultDepth    24

    Option         "TwinView" "0"

    Option         "metamodes" "1152x864 +0+0"

    SubSection     "Display"

        Depth       24

    EndSubSection

EndSection

Planning to use docky but resolution is so low that its waste to use it.