How to configure synaptics?

In Ubuntu 9.1, I noticed my touchpad was very jumpy. For some reason, I don't know how, my synaptics driver was a version from git, 1.1.99, and it did not have the JumpyCursorThreshold.

After experimenting, I've found that this command makes the settings about right:

 synclient JumpyCursorThreshold=100

But I'm a bit stumped on the "recommended" way to make that change permanent. My xorg.conf does not have any section on the touchpad, the only device control it has is a generic mouse looking thing:

Section "InputDevice"
    # generated from default
    Identifier "Mouse0"
    Driver "mouse"
    Option "Protocol" "auto"
    Option "Device" "/dev/psaux"
    Option "Emulate3Buttons" "no"
    Option "ZAxisMapping" "4 5"
EndSection

Am I supposed to put "Option JumpyCursorThreshold 100" in there?

Or in some hal file? or what?

Some clear guidance on what the experts want us to do would be appreciated.