Set up Xorg on Arch Linux

1. install xorg and your graphic card driver

sudo pacman -S xorg xf86-video-intel

2. auto-generate xorg.conf from detected result

Xorg -configure

3. DO NOT run test before hal or your keyboard and mouse will be freezed

Xorg -config filename

4. move the generated file to /etc/X11

sudo mv xorg.conf.new /etc/X11/xorg.conf

5. add the following setting to xorg.conf

vi /etc/X11/xorg.conf
--

..
Section "Module"
Load "glx"
..
..
Section "Monitor"
DisplaySize 336 210
..
..
Section "Screen"
SubSection "Display"
Modes "1280x800" "1024x768"
..

module glx is for 3d acceleration

in order to get correct sizing for fonts, the display size must be set for your desired dpi.
display size = (x|y)pixels * 25.4 / dpi
i'm running xorg with a resolution of 1280x800 and want a dpi of 96 so i use 1280 x 25.4 / 96 and 800 x 25.4 / 96

if you wish to use a lower resolution than your monitor is capable of, manually specify modes which you need only

6. edit /etc/rc.conf to load hal on boot

vi /etc/rc.conf
--

DAEMONS=(syslog-ng network netfs crond hal)