Issue with dual displays in Ubuntu 11.04

I recently upgraded from 10.10 to 11.04 and to my horror my dual display configuration doesn't work any longer. It took me a while to come up with the right settings under 10.10 when I installed it a few months ago - however that configuration now no longer seems to work under 11.04.

I've got a Radeon 9200 and am trying to get my desktop to stretch across two 1440x900 monitors side-by-side.

I've tried Xorg -configure which fails with an error. Neither the "monitors" nor xrandr allow me to define a setup that seems to work.

Funnily enough, using either of those two tools I am able to place stretch the desktop vertically??? I took some screenshots but can't attach them to the question?

On 10.10 I had a fairly simple xorg.conf file for the X configuration:

Section "Device"
    Identifier "Card0"
    Driver "radeon"
    Option "Monitor-VGA-0" "Envision"
    Option "Monitor-DVI-0" "Acer"
EndSection

Section "Monitor"
    Identifier "Envision"
    Option "PreferredMode" "1440x900"
    Option "RightOf" "Acer"
EndSection

Section "Monitor"
    Identifier "Acer"
    Option "PreferredMode" "1440x900"
EndSection

Section "Screen"
    Identifier "Screen 0"
    SubSection "Display"
        Virtual 2880 900
    EndSubSection
EndSection

Under 11.04, whether I have this config file in /etc/X11, the result is the same - no horizontally stretched desktop.

Any thoughts are appreciated.