Problem getting external monitor working with Linux

I've followed the various posts on using external monitors but still I can only get 1024x600 on my external monitor. I'm using a 19" LCD which has a native resolution of 1280x1024. I've shown the contents of the relevant files below.

I'd be very grateful for any suggestions!

Thanks

/etc/X11/xorg.conf

Code:

Section "Screen"
	Identifier "Screen0"
	Device     "Videocard0"
	Monitor	    "Monitor0"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     24
		Modes "1024x600" "1280x1024" "1024x768"
	 Virtual 1280 1024
	EndSubSection
EndSection

/usr/share/xfce-mcs-plugins/display_plugin_size.lst

Code:

1024x600
1280x1024
1024x768

 

There ought to be a modeline in the monitor section of your xorg.conf for the resolution 1024x600 which looks like this:

Code:

Modeline  "1024x600" 48.96 1024 1064 1168 1312 600 601 604 622 -HSync +VSync

Add another modeline below for your resolution with the appropriate parameters. For the meaning of the parameters, see the modeline section in the xorg.conf manual (man xorg.conf). The correct parameters depend on the characteristics of your external monitor, it may not be easy to find them out.

Hope, this helps!