How to change the default port number

hai all,
I need to change the default port number of the SQL server from 1433 to some other port number. i know that it can be done thru SERVER NETWORK UTILITY. Can some one confirm that. It will be helpful.
Also i want to make sure that port to given is free port. how can i find that particular port is free.

Thanking in Advance, awaiting Quick response.

Signing Off
Venkatesh.VYes, SERVER NETWORK UTILITY can do it.
U can make a program to test if the port is not be used.sql