Dual Head Xorg Config for a RadeonHD RV630 aka Radeon HD 2600XT

** Note ** I've sold this card since, but I'll repost this in case it is useful to anyone:
Just a reference in case anyone else is trying to figure out how to get dual head working (with screen stretch) on Ubuntu in particular since Ubuntu doesn’t figure it out by itself. Took me awhile to get this figured out.
The magic lines (in “Device") are this
Option "monitor-DVI-I_1/digital" "dvi1"
Option "monitor-DVI-I_2/digital" "dvi2"

Additionally, you need to add a “Virtual” to the “Screen” section of your first monitor to allow the driver to be prepared to draw across both screens.
Virtual 2560 1024

As you might expect, the monitors need a relative position to be stated. So the right side monitor (you guessed it, in section “Monitor") in my case has
Option "RightOf" "dvi1"

I’d post the whole file, but it’s a big mess with lots of stuff that would distract and confuse. Maybe I’ll clean it up later.