Thanks!
in etch, it is auto-configed
Now I want to config it in sarge. I enter
dpkg-reconfigure xserver-xfree86
but I don't know which mouse option I should select.
and which kernel module I should load?
In a text-mode VT, try the command "cat /dev/input/mice" and move your mouse; you should see ASCII garbage generated. (Ctrl-C to quit, followed by "reset" typed blindly if necessary.)
If that generates garbage, then "/dev/input/mice" is what you want in your config file. If it does not generate garbage, you may need to modprobe mouse or usbmouse or usbhid or any of several others; I never can remember exactly. You can install "modconf" and run it, and install any promising looking modules via a text-based "point-and-click" interface until you find the correct [combination of] module[s]. That's usually what I used to do.
If you have an Etch box running with a USB mouse, you can "lsmod" on that box and look for any relevant USB and/or mouse and/or input modules and try them on the Sarge box.