PS/2 mouse trouble

[LimaUnion]

Today I finished installing my second Ubuntu system and am having some 
minor trouble. This is a Compaq 700 notebook, with a synaptic touchpad 
and an external PS/2 mouse attached.

The installation was fine but the PS/2 mouse still doesn't work; 
previously I was running FC2 (hasta la vista baby ;) ) and I had in my 
grub.conf file psmouse.proto=imps to make it work correctly, but in 
Ubuntu it doesn't.

The driver 'psmouse' loads correctly but the mouse simply doesn't work, 
under /dev is 'psaux' and my XFree86 file looks like this:

> Section "InputDevice"
>         Identifier      "Configured Mouse"
>         Driver          "mouse"
>         Option          "CorePointer"
>         Option          "Device"                "/dev/input/mice"
>         Option          "Protocol"              "ImPS/2"
>         Option          "Emulate3Buttons"       "true"
>         Option          "ZAxisMapping"          "4 5"
> EndSection
> Section "InputDevice"
>         Identifier      "Generic Mouse"
>         Driver          "mouse"
>         Option          "SendCoreEvents"        "true"
>         Option          "Device"                "/dev/psaux"
>         Option          "Protocol"              "ImPS/2"
>         Option          "Emulate3Buttons"       "true"
>         Option          "ZAxisMapping"          "4 5"
> EndSection
> Section "InputDevice"
>         Identifier      "Synaptics Touchpad"
>         Driver          "synaptics"
>         Option          "SendCoreEvents"        "true"
>         Option          "Device"                "/dev/psaux"
>         Option          "Protocol"              "auto-dev"

Thanks in advance for any comment/suggestion.
JC