Well I can understand what you mean, as I have played RuneScape for over a year, and I have seen the word noob everywhere, especially when people are angry at others. Back when I was level 80+, a guy wanted to buy my whip (worth about 3 million, very good weapon, hard to come by at a good price), and when I said no, he called me a noob and ran off. He had maybe 10 more levels than me, maybe less.
Then again, I now play Conquer Online, and in there, noob is mainly used to designate low level players, and generally it doesn't have a bad connotation. Actually, I've hardly ever seen it used in a bad way.
And just like everyone else said, newbie and noob are completely different. Newbie is a new player, and it isn't an insult, more of an excuse. Noob, is usually either a low level player, or simply somebody who is annoying (people who follow you around for hours asking the same question, and just can't seem to understand that we don't want to be bugged. Its also for beggars, those who continuously beg for money or items).
It really shouldn't be an insult to you. Also, in this game I have yet to see noob in the chat box.