I wanted to try to setup my dual-head configuration using xrandr, instead of aticonfig (using the 9.3 fglrx driver). So I reconfigured using:

aticonfig --set-pcs-str="DDX,EnableRandr12,TRUE"
As I understood, this is necessary to enable Randr 1.2.
Thereafter I made a backup of my xorg.conf, removed and did:

aticonfig --initial --adapter=0 -f
To force a clean xorg.conf.
Now I had my monitor working and by default my tv shows a cloned image.

So, I tried to setup my tv-out, but I get the following error message:

xrandr --addmode S-video 800x600
xrandr: cannot find output "S-video"
When I query xrandr I get the following:
xrandr -q
Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm
   1280x1024      75.0*    60.0  
   1280x960       60.0  
   1280x768       60.0  
   1280x720       60.0  
   1152x864       75.0     60.0  
   1024x768       75.0     70.0     60.0  
   800x600        75.0     72.0     60.0  
   720x576        50.0  
   720x480        60.0  
   640x480        75.0     72.0     60.0  
   640x432        60.0  
   640x400        75.0     60.0  
   640x350        70.0  
   512x384        75.0     60.0  
   400x300        75.0     60.0  
   320x240        75.0     60.0  
   320x200        75.0     60.0
Is there anything I'm doing wrong? My tv is connected via a composite/s-video output on my HD3450. My motherboard contains an HD3200 as well, there is no monitor connected to the HD3200 but I am using hybrid crossfire and that is working fine.