Just put together a PC and I'm having problems with X behaving properly
	with the built in PS/2 mouse.

	X appears to be reading from the device but the pointer moves in a random
	fashion.

Check that you have the right mouse protocol selected in your
XF86Config file.  In my experience, you cannot reliably deduce the
correct protocol selection from anything other than exhaustive
search:  I have a mouse that clearly says "Logitech" on it, but
seemingly does not speak "Logitech"; it plugs into a PS/2 mouse
port, but seemingly does not speak "PS/2".  If I recall correctly,
X thinks it speaks "Bus mouse" (or maybe "Mouse Systems", I forget).

Dave