ok , i found the solution from my question and thinking it might be helpful if anyone encounter the same problem like this.
remote xp ip =192.168.1.5
workgrp xp ip=192.168.50.222
firewall sshdserver ip = 18.104.22.168
1) workgrp computer need not to do anything.
2) merely configure putty on the remote xp .
--> in tunnel pages, make sure you have source 127.0.0.2:60001
--> destinatino , is 192.168.50.222:3389
3) connect to sshd in firewall server .
4) open MS remote desktop and type in 127.0.0.2:60001
OK, you will wonder why 127.0.0.2 ? Because default 127.0.0.1 won't work for some strange reason. I got this from an article:
Hope this help !