Disable Middle Mouse Paste

[kripz]

My touchpad looks like this:

______________
|        |   |
|        |   |
|________| V |
|            |
|______H_____|

The usual touchpad with special scrolling sections (H, V).

Using xev my touchpad is mapped as following:

Left Click: 1
Right Click: 3
Left + Right Click: 2

Scroll Down: 5
Scroll Up: 4
Scroll Left: 6
Scroll Right: 7

Tapping the scrollling section in different parts results in different buttons.

Vertical Scroll:
Very top: 2
Between top and bottom: 1
Very bottom: 3

Horizontal Scroll:
No events are fired.

Usually when using my laptop, i only scroll using the very top of the scroll section, this results me in pasting random stuff all time time.

How can i disable this?

Im running Xubuntu 8.04.

Current Xorg.conf:

# 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"
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" "1"
EndSection

Section "Device"
Identifier "Configured Video Device"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
InputDevice "Synaptics Touchpad"
EndSection