Install X window system

X window system could be installed in a single easy step.

I would prefer installing video driver before installing x system though in the official archwiki official guide, installing video driver comes after installing x system.

So here it is.

# pacman -S xorg-server xorg-xinit xorg-server-utils

This one liner makes it all possible.

Now your x environment doesn't contain any applications which you can test on your monitor. You can install any basic applications available with x environment.

# pacman -S xorg-twm xorg-xclock xterm

This installs,
twm - Timeless Windows Manager, the standard window manager for the X Window System
xclock - GUI clock for the X Window System
xterm - Terminal emulator for the X Window System

Install dbus

D-Bus is a message bus system that provides an easy way for inter-process communication. There is a high change that if would have already been installed but anyways go ahead and check.

Install dbus:

# pacman -S dbus

Start the dbus daemon:

# rc.d start dbus

Add dbus to the DAEMONS array in /etc/rc.conf so it starts automatically on boot:

DAEMONS=(... dbus ...)

Test X environment

You can test the environment now with this simple command

# startx

Note:
If Xorg was installed before creating the non-root user, there will be a template .xinitrc file in your home directory that needs to be either deleted or edited in order to start X. Simply deleting it will cause X to run with the default environment installed above.

$ rm ~/.xinitrc