Press and hold the windows key, and press the PAUSE/BREAK button. It is located up near the ScrLk (Scroll Lock). If that doesn't work click your start button, right click COMPUTER, select properties.
This will bring up the System Properties windows.
In the top left hand corner there will be a link to the device manager. Click it.
Dig through the device manager until you find the section named PORTS.
Find the port you want to change, right click it and select properties.
Select the Port Settings Tab.
Click the Advanced button.
Change the port number.
You might be prompted to restart your system.
This is from memory, so it might not be exact. Good Luck.