Update. For a better solution, see this blog.

Our office has a (2002) older Toshiba Satellite 1405-S151. Windows XP is unbearably slow on the laptop, so I wanted to see if it was usable with a current version (9.04) of Ubuntu. The installation went pretty smoothly, and the computer worked much better than with Windows, except for the screen, which was stuck on 800×600 resolution.

After spending a considerable amount of time trying to figure out how to fix things, I was able to come up with this solution, borrowing from several forum posts.

The solution requires an edit of the xorg.conf file, which is found here: /etc/x11/xorg.conf

But first, it is alway a good idea to back up the existing file. My backup was xorg.conf.backup

Before the change, the relevant text in xorg.conf read like this:

Section “Device”
Identifier “Configured Video Device”
EndSection

Section “Monitor”
Identifier “Configured Monitor”
EndSection

Section “Screen”
Identifier “Default Screen”
Monitor “Configured Monitor”
Device “Configured Video Device”
EndSection

Based upon some things that worked on different computers using the same video card, I finally tried the following, which seems to work.

Section “Device”
Identifier “Trident Microsystems CyberBlade XPAi1″
Driver “trident”
BusID “PCI:1:0:0″
EndSection

Section “Monitor”
Identifier “Generic Monitor”
Option “DPMS”
HorizSync 28-51
VertRefresh 43-60
EndSection

Section “Screen”
Identifier “Default Screen”
Monitor “Generic Monitor”
Device “Trident Microsystems CyberBlade XPAi1″
SubSection “Display”
Depth 8
Modes “1024×768″
EndSubSection
SubSection “Display”
Depth 16
Modes “1024×768″
EndSubSection
EndSection

I now have the laptop using the whole screen in a 1024×768 mode. It is much faster and more reliable than anything I could make work in Windows.