On Wed, 19 Jan 2011, Chuck Guzis wrote:
If you're running XP on it, it can't be that
old (unless I've misread
your initial description of what you're doing). Even relatively
inexpensive P1 systems at least had headers on the motherboard for a
PS/2 mouse, if not an outright connector. Many early AT enclosures,
however didn't leave a hole next to the keyboard jack for the mouse,
so you may want to have a look. If it's an ATX-layout machine, then
for certain there's a mouse jack there.
. . . and if it were an old machine, you could use a "bus" mouse.