running slackware 9... when I installed it I used a PS/2 mouse.. I now have a USB mouse.. how do I make it work

You need to make sure you are loading the usb modules. If you are running hotplug, this should be happening already. If you are not, then you will need to uncomment those lines in /etc/rc.d/rc.modules. Next I would run mouseconfig, or at least make sure /dev/mouse is now a symlink to /dev/input/mice. You may have to next edit your /etc/X11/XF86Config to make sure the pointer section has the appropriate identifiers.

I read a past post and it worked perfectly to my.
just add this to xorg.conf file

Section "InputDevice" ----->add all this block
# External USB mouse using usbhid/mousedev
Driver "mouse"
Identifier "USBMouse"
Option "Device" "/dev/input/mice"
Option "Protocol" "ImPS/2"
Option "Buttons" "3"
Option "ZAxisMapping" "4 5"
EndSection

Section "ServerLayout"
Identifier "MyLayout"
InputDevice "Keyboard" "CoreKeyboard"
InputDevice "TrackPoint" "CorePointer"
InputDevice "USBMouse" "SendCoreEvents" ---------------------------->this is what you add
Screen "Screen[0]"
EndSection

where exactly is xorg.conf I've never really done anything with that... ?

(I havn't used linux in quite some time... *sigh* I need more spare time)

it should be located at /etc/X11, into there should be xorg.config or xf86config, but I don't know if that configuration that I posted works with xf86config

whats the difference between xorg.config and XF86config?

the diference is that xorg is in someways the other path that took xf86 for legal reasons or something about license it has to take this other path.

but in short words is the samething at least for now

the name basicaly. Xorg is what slack10 uses. Slack9 used xfree86. The config files are setup the same.

Also you should look in /etc/rc.d/rc.modules and make sure you have the USB mouse driver set to load.