One problem with my Ubunto installation on my laptop is that the max resolution I can set was 1024x768 which is pretty crowded for soing software development in Eclipse. So I followed the instructions in FixVideoResolutionHowto - Community Ubuntu Documentation:

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.custom
sudo sh -c 'md5sum /etc/X11/xorg.conf > /var/lib/x11/xorg.conf.md5sum'
sudo dpkg-reconfigure xserver-xorg

update Well, that worked, but not without problems. I was asked a daunting amount of questions by the dpkg-reconfigure xserver-xorg program. When asked what were the allowed resolutions I just selected everything -- the instructions seemed to suggest that was safe. I suppose I should have rebooted into Windows to check what are reeally allowed. Now I do get Ubuntu running in higher resolution, though a bit distorted I think because the aspect ratio is not quite right. However if I try to change the resolution using the Preferences UI the computer freezes and has to be hard-reset.

update 2 Firstly, I forgot to mention that I needed to to a CTRL-ALT-BACKSPACE to restart X to see the effect of the above change.

Secondly, a strong warning: when I tried to do this on a desktop machine on which I was installing Ubuntu a few days later it killed X and threw me back to the command line. I think it was because I chose the option to automatically detect the monitor. In that case all I really wanted to do was increase the monitor refresh rate to avoid an annoying flickr. So after the above technique failed I instead I edited the /etc/X11/xorg.conf config script modifing the monitor refresh rate line to

VertRefresh     43-85

and restarted X. That seems to have worked fine.