Variant spellings, such as newb, nub, noob, nooblet, foob, noobcake , noobstain and, in Leetspeak, n00b are numerous and common in Internet use. The term newb itself is usually used to refer to a person who is new to the field in question, whereas noob is used as an insult. For example, in the internet show Pure Pwnage, the main character regularly says, I pwn noobs, in this case, meaning he beats people of lower skill than himself.
From http://en.wikipedia.org/wiki/N00bWiki