Same as everyone else with any computer with Windows XP installed..
When you turn on the computer, right after the BIOS post, start tapping your
F8 key to get a menu of choices for booting. You will find what you need
there.
A Google search for "boot Windows XP in Safe Mode" will give you hundreds of
hits on sites telling you exactly how to do what I just described, some in
excruciating detail.