In Ubuntu 10.4 Lucid Lynx, if someone need to change the display settings, you may find useful the /etc/vga/libvga.config file .

In fact, in version 10.04, /etc/X11/xorg.conf no longer exists, but resolution is defined in libvga.config , with also settings for mouse and keybord.

For example, my resolution i defined as

# Monitor type:

# Only one range can be specified for the moment. Format:
# HorizSync min_kHz max_kHz
# VertRefresh min_Hz max_Hz

# Typical Horizontal sync ranges
# (Consult your monitor manual for Vertical sync ranges)
#
# 31.5 – 31.5 kHz (Standard VGA monitor, 640×480 @ 60 Hz)
# 31.5 – 35.1 kHz (Old SVGA monitor, 800×600 @ 56 Hz)
# 31.5 – 35.5 kHz (Low-end SVGA, 8514, 1024×768 @ 43 Hz interlaced)
# 31.5 – 37.9 kHz (SVGA monitor, 800×600 @ 60 Hz, 640×480 @ 72 Hz)
# 31.5 – 48.3 kHz (SVGA non-interlaced, 800×600 @ 72 Hz, 1024×768 @ 60 Hz)
# 31.5 – 56.0 kHz (high frequency, 1024×768 @ 70 Hz)
# 31.5 – ???? kHz (1024×768 @ 72 Hz)
# 31.5 – 64.3 kHz (1280×1024 @ 60 Hz)

HorizSync 31.5 35.5
VertRefresh 50 90