But I don' t know that much, that I could start my second monitor works. I looking for solutions almost everywhere. but nothing works for me. I already give up and you are my last chance. so I ask you. can anybody help me ?
Problem specification: how to edit Xorg.conf or where or which driver install for dual monitors could works.
Info about monitors, system notebook which I can provide:
Notebook: Compaq pressario CQ60, with graphic card: Nvidia GeForce 8200m g, 4GB RAM, 2 CPU.
Monitor: LG 24" with HDMI cable connected to notebook.
lspci | grep VGA - Told me this.
02:00.0 VGA compatible controller: NVIDIA Corporation C77 [GeForce 8200M G] (rev a2)
driver version is; 310.14
system: Release 14 (nadia) 32-bit, Kernel Linux 3.5.0-17-generic, GNOME 3.6.0
if I remember corectly ... dual monitors works in Ubuntu with default Ubuntu driver. After I installed the newest, second monitor shows me only black screen.
I hope this is exhaustive information I could give you. oou Last thing: I am really sorry for my English, I am not native speaker but I do my best.

