England begin the 2007 tournament in France next Saturday with Ashton admitting that being the defending champions but ranked just seventh in the world is an "interesting mix."
But he added: "A lot of people have forgotten we are world champions and we are defending the title.
"No-one's ever done that before and what a fantastic opportunity for a team that has been written off all over the world to actually go out and do something like that.
"I think they will use it as a motivation. We've not talked about it publicly but there are a significant number of players who were there in 2003 and I'm sure it will cross their minds at some stage."
Ashton has only had a short time to mould his squad since replacing Sir Clive Woodward's successor Andy Robinson, who was dismissed after the disappointing autumn internationals.
A resounding victory over Wales was put into perspective by two defeats against World Cup hosts France in the warm-up matches.
But Ashton maintained: "We're not that far away from where we wanted to be. We know the steps we've got to take to get where we want to be and we'll just make sure we do it."
He is not concerned what his rivals think about England's prospects or their preparation, adding: "Honestly, it doesn't bother me.
"I'm not interested in what other people think of England. I wish I had the time to think about the other teams."
Responding to criticism from Eddie Jones, coach of the Australian team beaten by Woodward's England in the 2003 final, Ashton explained that he gave his players 10 days off following the 22-9 defeat by France in Marseille because it was the right thing to do.
Ashton explained: "The World Cup starts next week and we've done seven weeks training, played three back-to-back Test matches and these guys are in pretty good shape. They need to rest as much as train at the moment.
"I really don't mind what other coaches say about what we should be doing. We'll just get on with developing our team the way we think best."
If Leicester's Martin Corry resumes full contact training next Tuesday or Wednesday following his knee injury, England will go into next Saturday's opening pool match against the USA in Lens with a fully-fit squad of 30.
Ashton, who has already made up his mind about the starting line-up, intends to let the players know on Tuesday.
He will also tell them there is still a lot of work to do.
England have to fix the line-out which malfunctioned in Marseille and the coach wants them to create more running opportunities for potential match-winners like Jason Robinson.
"We are a side of players who came together three weeks ago, have played three games with different personnel each time and are a team that has evolved," said Ashton.
"We had to start to get the basics of our game right and I think we've done that. We've now got to move on fairly smartly from that.
"We've got to make the leap from just playing together to actually having complete confidence and trust in one another.
"We know that and I believe we've got the players to do it."