Okay,
I've got a newer laptop, brand is Clevo (at least in France):
http://www.clevo.fr/
12 inches screen, nice little machine. But I can't get a 1280-8OO resolution, just the 1024-768, so gnome is truncated. and fills 3 quarters of the screen.
What tried so far :
dpkg-reconfigure x-server-xorg --> no luck
Manually editing my xorg.conf --> no luck
Adding modelines ---> no luck either
As this is a GM 965 architecture, installing i915resolution --> no luck.
I'm completely at a loss here. Also tried with Ubuntu own tools to get a change. Any suggestions, people.
On the positive side, the wireless worked at first try, and all the rest is fine.
Thanks in advance.
cheers

A 12 inch screen and a resolution of 1280-800? A bit too much I would say. Could it be that your system refuses your wish because it is impossible?
I solve the problem by managing my screen stretching it to the left, right, up and down. Surely a modern laptop has the same tools for this problem as my more than six years old monitor.

Thanks for your answer. The problem is that I can't seem to "stretch" the screen towards the right. I'll look in it more.
cheers

PS After looking in the handbook, the mx resolution is really 1280 - 800

on alot of laptop BIOS on the CMOS Setup. you will see sometime screen stretch enable it. then save setting reboot. make sure if running linux to set to non plug and play system or non windows so linux can read the bios correctley