adding an xp computer to a fixed ip network

I have an existing home network using fixed ip. The network consists of a router, one win 98 computer and
two linux computers. I recently got a hand-me-down xp
computer I would like to add to it.

The wizards in xp apparently assume dhcp. How does one assign fixed ip addresses in windows xp ? The router did come with a setup disk, which is how I configured the 98 computer. However, I seem to have misplaced the disk.