Adjusting mouse sensitivity

[Adam]

Hi,
I bought a cheap wireless laptop mouse from ebay and I'm having trouble
adjusting the sensitivity in xfce.
I'm running xorg-server 1.3, the kernel is gentoo-sources-2.6.27-r8
x86_64 and I'm running xfce 4.4.3.

I can get into the mouse settings and adjust the acceleration and
threshold, but the settings have no affect, even after restarting the
xfce session.

Here is my mouse section in xorg.conf

Section "InputDevice"
        Identifier      "USBMouse"
        Driver  "mouse"
        Option  "Device" "/dev/input/mice"
        Option  "Protocol" "auto"
        Option  "ZAxisMapping" "4 5"
EndSection


I've also tried adding sensitivity and resolution options to xorg.conf,
but these also have no affect. The mouse is much to sensitive for my
liking and if I can't find a way to reduce the sensitivity the mouse is
not that useful to me.

Any help would be appreciated.