I am using following command to change my screen resolution:

xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync

xrandr --addmode VGA1 1368x768_60.00

xrandr --output VGA1 --mode 1368x768_60.00

Now, which file do I need to edit so it will modify my screen resolution when I start up my Ubuntu PC?

NOTE: editing .xprofile isn't ideal since it's only per-user, not system-wide, and GDM/KDM doesn't existed on a vanilla 11.10 install, nor does xorg.conf