Actually, if they get a PM containing the rules (with a "hello, welcome to the forums" as title, to make them read it, lol), they'll at least know about the rules. Not having read the PM is not an excuse.
Well, it's better than what we have now, at least, c'mon, you have to search the forums to find the rules... How many noobs even want to look at site discussion? "ZOMG GAMEZ KORNORZ LOLZORZ!!!!11"
I have already suggested an announcement, but I know it might be annoying for those who are familiar with the rules, as it take up place. Nevertheless, I still want a link to the rules in an announcement at the top of every page like the spelling and grammar message.