remote FTP connection(using client filezilla) to xampp with FTP server(filezilla) is not working

Dear Expert,

I have successfully setup xampp, FTP server using filezilla on my window xp and
I tried client filezilla on the same computer using localhost and type correct
username and passwd,port number 21 and finally succesfully get the my expect ftp directory that is setup on ftp server setup on xampp-control panel.
Now I tried to use the other computer using window 7 and then use
client filezilla and type the server address( that is NOT localhost and that should be the ip address of the previous window xp computer ) and then type the same user name and passwd ,port num 21as I did but it fail to get ftp directory on other computer
 (but okay if do it on the same computer)
Why ?


So now I go to check window xp firewall and do some exception for filezilla on the window xp computer. And then try again client fillzilla on the othe window 7 computer, but it
doesn't connect either ....Why?

So I check ping the ip address for  window xp computer  that is okay and active.
When I type localhost on webbrowser on xp computer that is also showing the index.php page for me. so all setup for ftp server and apache server with xampp on xp is fine
But why external other PC can not connect to the FTP server on xampp on window xp computer ?

Please advise

DUncan