(this works on NT, 2000 and XP)
Go to a command prompt and do a "netstat". You will see a list of results like this.
Proto Local Address Foreign Address State
TCP yourhost:3152 irc.dal.net:6666 ESTABLISHED
TCP yourhost:3977 xx.92.244.xx:ftp FIN_WAIT_2
TCP yourhost:3978 xx.92.244.xx:ftp TIME_WAIT
TCP yourhost:3985 xx.92.244.xx:ftp ESTABLISHED
TCP yourhost:3987 xx.92.244.xx:ftp ESTABLISHED
TCP yourhost:3996 forums.mirc.com:http CLOSE_WAIT
On the left side where you see the numbers after "yourhost" this is the port your client is using for the connection. The port on the right column shows THEIR port, and has NOTHING to do with the limits in YOUR client.