Instructions for upgrading can be found in this PDF document. You will need Adobe Acrobat reader to read the document. You will also need this windows program. (TFD-Down.exe as mentioned in the download manual).
You will also need the latest firmware which was released on July 30th 2004.
You can't tell by just looking at it, unless the cable is marked as a null cable along its length as some are. You could test your cable by connecting your PC to a serial modem with it. If the cable works and your PC can communicate with the modem, log onto the net etc, then your cable is not a null modem.
If the plugs are not solid state you could open them and check to see which pin each coloured cable is connected to on each end as in the pin connections in my previous post.