msn does not connect through port80. port 80 is only a tcp port.
msn will use port 1863. You can use netstat to determine ports needed.
eg:
[code:1]
[seb@localhost seb]$ netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 localhost.localdoma:783 *:* LISTEN
tcp 0 0 *:x11 *:* LISTEN
tcp 0 0 192.168.1.102:32795 207.46.108.72:1863 ESTABLISHED
tcp 0 0 192.168.1.102:32788 baym-cs86.msgr.hot:1863 ESTABLISHED
tcp 0 0 192.168.1.102:32796 210.18.204.91:http ESTABLISHED
tcp 0 0 192.168.1.102:32789 207.46.107.17:1863 ESTABLISHED
udp 0 0 *:who *:*
udp 0 0 *:685 *:*
udp 0 0 *:bootpc *:*[/code:1]
