dual head using HDMI output on ati radeon 5470

[Albert Wagner]

I have Ubuntu 10.10 running on an HP G72 laptop with vga and HDMI  
outputs from an ATI Radeon 5470.  Dual heads is simple with vga: just 
use System->Preferences->Monitors.  But, getting anything at all from 
the HDMI output is proving to be very difficult.

My digital monitor is an HP 2310e that looks outstanding when driven by 
a dvi input on another machine.  But it has only digital inputs, no vga.

I would really appreciate feedback from anyone using the Ubuntu Radeon 
driver(KMS on is default) as to whether, and how, it can be coerced to 
detect the HP 2310e and output through the Radeon 5470 HDMI plug.