I would not rely on that website to use your serial number. It is not secure.
Your serial number is one means of getting info about your warranty.
For a brand new machine only use Apple's website to look up the serial number on their support page:
http://www.apple.com/support/
Mind you, Apple's serial numbers are easy enough for the user to decode:
xxABCxxxx (sometimes additional digits follow), where x is any letter or number, A = last digit of year, BC = two numbers for week of year. So xx025xxxx is the 25th week of 2010.
Once you know your year and week, you can easily guess the MacBook Pro model you actually have.