How can I increase the monitor resolution of my netbook?

[DeepSeaNautilus]

I have ubuntu 8.10 installed on an acer aspire one. I have connected an external screen to the netbook's vga port, but the resolution is very low and I don't know how to change it because in the system>screen resolution application, the highest resolution available is 800x600, which is my current resolution.


$ lspci | grep -i 'graphics'
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GME Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)

$ cat /etc/X11/xorg.c
Section "Device"
Identifier "Configured Video Device"
Option "MonitorLayout" "LVDS,VGA"
Option "Clone" "True"
Option "AccelMethod" "EXA"
Option "MigrationHueristic" "greedy"
Option "CacheLines" "1980"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection


$ xrandr
Screen 0: minimum 320 x 200, current 800 x 600, maximum 1600 x 1600
VGA connected 800x600+0+0 (normal left inverted right x axis y axis) 410mm x 257mm
1440x900 59.9 + 75.0 59.9 60.0
1600x1024 60.2
1400x1050 60.0
1280x1024 75.0 60.0 60.0
1280x960 60.0 60.0
1360x768 59.8
1152x864 75.0 75.0 75.0 70.0 60.0
1024x768 75.1 75.0 70.1 60.0
832x624 74.6
800x600 72.2 75.0 60.3* 56.2
640x480 75.0 72.8 72.8 75.0 66.7 60.0 59.9
720x400 70.1
LVDS connected 800x600+0+0 (normal left inverted right x axis y axis) 195mm x 113mm
1024x600 60.0 +
800x600 60.3*
640x480 59.9


How can I change the resolution of the external screen only to those displayed by the xrand command and how can I configure the monitor and the screen separately?

I think this can be solved by editing the xorg.conf to the proper configuration, but I am not sure how to configure it properly, can anyone tell me how to configure this file to solve my problem or if there is any other way to fix this? Thanks in advance

[DeepSeaNautilus]

OK, I am answering myself so others can benefit. Reading the xrandr man page I found that It does not only inform about the valid screen resolutions, but can also change the resolution for a specified screen and many other operations. If the desired resolution is already registered, simply type:
xrandr --output <screen> --mode <resolution>

Worked great for me :), and works much better than it does in windows xp (just like the wifi adapter by the way) even when I tried with all the available resolutions.