function of xorg.conf in sid?

[Paul Scott <waterhorse@ultrasw.com>]

I recently posted about not being able to get full resolution of my 
Portege 4010 with dpkg-reconfigure.  I found an example of xorg.conf 
sections which solved my resolution problem but:!!!

I still don't know why 'dpkg-reconfigure -p<high|medium|low> 
xserver-org' gives me no opportunity to change any video parameters.  I 
saw an Ubuntu post suggesting that xorg.conf wasn't completely necessary 
and indeed I was able to run my system at default resolution without it.

TIA for any more information,

Paul Scott