Instead of using aticonfig to setup a dual-head configuration, I would like to use xrandr to do the same thing. I was wondering if this is possible. I'm looking for a setup with two separate desktops (no window dragging from one monitor to another, so I am NOT looking for a single large desktop).

Using aticonfig I can setup a dual-head configuration using:
aticonfig --initial=dual-head -f
In my xorg.conf this gives me 2 screen sections, 2 monitor sections and 2 device sections. In the serverlayout section both screens are listed. With xrandr I'm able to address the separate screens with the option `--screen 0' and `--screen 1'.
But with the newest fglrx drivers I'm experiencing problems after configuring my dual-head setup this way (gnome only uses 1024x768 pixels of the 1280x1024 pixels that show up on my monitor).

So I was wondering if I could achieve the same dual-head setup with xrandr. So I did:
aticonfig --intial -f
And my main monitor works fine. My xorg.conf only has one screen, monitor and device section and only one screen is listed in the serverlayout. Now I would like to add a 2nd X screen for the second desktop, using xrandr. How should I do this, and is this even possible?

I can't find much information about this topic because almost everybody seems to want to stretch their desktop over multiple screens. I don't want that because one of my monitors is my TV, which is often turned off and I don't accidentally drag windows to them. I don't want a setup with cloning the screens either, because I like to use my main monitor while I'm playing a movie on my tv.