If I understand you correctly, you want to run an X11 application on your Linux machine, tunnel it through SSH and let the display appear on your XP machine.
I only did that once, just to play around with it, and it's years ago...
* There are several X11 implementations for Microsoft Windows, but most of them are non-free and quite expensive. I have forgotten which one I tried, but it wasn't a full version either.
I guess, Cygwin/X is a good choice, but never tried it:
* On your Linux machine, enable ssh to do X11 forwarding in /etc/ssh/sshd_config
to your Linux machine and log in. Having done so, you have to set the shell variable DISPLAY to export your X display to your XP machine with Cygwin/X.
Given your XP box's hostname is xpbox and the network is homelan, then type $ export DISPLAY=xpbox.homelan:0
Henceforth, every X application should be displayed on your Windows box
If you want your whole Linux desktop to appear on your XP machine, just use VNC, it's available for both Windows and Linux.