Google shows URL without "www"

[LastDuaL]

Hi! I'm a new webmaster with a recent site (less than a month old) that is showing up in google, but without the "www" before the domain. I ran a check on one of my competitors and their no-www domain has zero PR while their www.domain has a PR4.

All the links I've built so far (except one that a friend posted) are to the www.domain site, so why does google list the site without the www? Does the url that Google shows reflect the url with the most links or simply whatever URL they noticed first (in which case all the links I've built to the www.domain url would be worthless?...confused)?