LinuxQuestions.org - Higher resolution

First of all: does your monitor support 1600x1200?
If so, edit /etc/X11/XF86Config-4 (or possibkl xorg.conf)
Look for Section "Screen"
Here's mine:

Code:

Section "Screen"

  Identifier "Screen0"

  Device "Card0"

  Monitor "Monitor0"

  DefaultColorDepth 16

  SubSection "Display"

  Depth 15

  Modes "1024x768"

  EndSubSection

  SubSection "Display"

  Depth 16

  Modes "1280x1024" "1024x768"

  EndSubSection

  SubSection "Display"

  Depth 24

  Modes "1024x768"

  EndSubSection

  SubSection "Display"

  Depth 32

  Modes "1024x768"

  EndSubSection

Choose your colour depth, and change Modes to what you want.

Second question: You need nVidias driver to do that, I don't know if they're included in Kubuntu.
Look for Section "Device" in same file as above; again, here's mine:

Code:

  Option "NoLogo" "false"

  Option "IgnoreEdid" "true" # needs to be true for some nvidia cards

  Identifier  "Card0"

  Driver "i810"

  BoardName "unknown"

 #BusID  "PCI:1:0:0"

EndSection

If Driver is "nvidia" then you have the correct one.
If it's "nv", you could try changing to "nvidia" and restart X. If you don't have nvidia-driver installed, X won't startup.
If so, go to Nvidias homepage, download driver and follow instructions. (This is very easily done.)
Then add to Section Screen(we're still talking bout same file, XF86Config-4):
(And this time an example from my nVidia-computer: )

Code:

 # Only the official NVIDIA driver supports twinview

  # these setting are an example

  Option "TwinView" "true"

  Option "SecondMonitorVendorName" "unknown"

  Option "SecondMonitorModelName" "unknown"

  Option "SecondMonitorHorizSync" "30-82"

  Option "SecondMonitorVertRefresh" "50-75"

  Option "MetaModes" "1024x768, 1024x768; 800x600, 800x600; 640x480, 640x480"

  Option "TwinViewOrientation" "RightOf"

  Option "ConnectedMonitor" "crt,crt"

EndSection

You will have to check HorizSync and VertRefresh, don't put them too high or you might fry your monitor!
That line w "MetaModes":
I think you should use
Option "MetaModes" "1600x1200, 1280x1024@1280x1024" (If you want second monitor fixed size)
or
Option "MetaModes" "1600x1200, 1280x1024" (If you want second monitor floating desktop)
And finally, Option "ConnectedMonitor" "crt,crt" change it to what you have:
crt=old type monitor
dfp= digital flat panel
tv=tv