I have been refurbishing these computers for over a year now and would like to help anyone who needs help with these machines.

Here is an xorg.conf that works flawlessly with Dell Latitude 640s & 600s.
Code:
# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg
Section "InputDevice"
Identifier      "Generic Keyboard"
Driver          "kbd"
Option          "XkbRules"    "xorg"
Option          "XkbModel"    "pc105"
Option          "XkbLayout"   "us"
Option          "XkbVariant"  "intl"
Option          "XkbOptions"  "lv3:ralt_switch"
EndSection
Section "InputDevice"
Identifier      "Configured Mouse"
Driver          "mouse"
Option          "CorePointer"
EndSection
Section "InputDevice"
Identifier      "Synaptics Touchpad"
Driver          "synaptics"
Option          "SendCoreEvents"      "true"
Option          "Device"              "/dev/psaux"
Option          "Protocol"            "auto-dev"
Option          "HorizEdgeScroll"     "0"
EndSection
Section "Device"
Identifier      "ATI Technologies, Inc. Rage Mobility M3 (AGP)"
Driver          "ati"
BusID           "PCI:1:0:0"
EndSection
Section "Monitor"
Identifier      "Generic Monitor"
Option          "DPMS"
HorizSync       28-51
VertRefresh     43-60
EndSection
Section "Screen"
Identifier      "Default Screen"
Device          "ATI Technologies, Inc. Rage Mobility M3 (AGP)"
Monitor         "Generic Monitor"
DefaultDepth    24
SubSection "Display"
Depth           1
Modes           "1024x768"
EndSubSection
SubSection "Display"
Depth           4
Modes           "1024x768"
EndSubSection
SubSection "Display"
Depth           8
Modes           "1024x768"
EndSubSection
SubSection "Display"
Depth           15
Modes           "1024x768"
EndSubSection
SubSection "Display"
Depth           16
Modes           "1024x768"
EndSubSection
SubSection "Display"
Depth           24
Modes           "1024x768"
EndSubSection
EndSection
Section "ServerLayout"
Identifier      "Default Layout"
Screen          "Default Screen"
InputDevice     "Generic Keyboard"
InputDevice     "Configured Mouse"
InputDevice     "Synaptics Touchpad"
EndSection
Section "DRI"
Mode    0666
EndSection