If, as expected, Les Bleus beat Wales, Ireland would have to dispatch the World Cup holders by at least 30 points to claim their first tournament crown since 1985.
The likelihood of such a scenario unfolding is remote, even allowing for England's poor form, but were Wales to spring an upset in Cardiff it would be game on.
Victory at Twickenham would still deliver a second Triple Crown in three years, however, and Murphy insists the fixture itself is enough to fire Irish ambition.
"Everything is there for the taking. Everyone is excited by the prospect of next weekend," he said.
"It's always huge at Twickenham against England - for any country but especially Ireland. We would be looking forward to the game even if nothing was on the line. It's a huge match.
"People are saying there are four million sets of fingers crossed for us next weekend. We have the support of the public behind us and all the guys want to get over there and play."
Ireland kept their title aspirations alive with a 15-9 victory over Scotland in a scoreline that failed to reflect their domination.
Fly-half Ronan O'Gara kicked all the points as conditions became increasingly unplayable, but Ireland showed enough tactical nous to shut out the Scots.
"The conditions were pretty horrible and it was a typical Lansdowne day," he said.
"The conditions meant it was never going to be an entertaining game, especially with Scotland's defence proving so strong. We just had to grind out a win.
"The ball was like a bar of soap - wet, greasy and there was a little bit of wind as well so the ball moved in the air.
"It was difficult to handle and we had to address that in the second half when we kicked a lot more ball. We played to win and were happy to get the victory.
"It was close on the scoreboard but we kept them at bay comfortably. We had the wind behind us and when they made mistakes it was difficult for them.
"I never felt we were under massive threat - any team in the world would have struggled to put together a lot of passes in those conditions.
"It would have been nice to get a few more points on the board but we were in command."
It was a predictable RBS 6 Nations send-off for Lansdowne Road, which can become hellish when inclement weather sets in, and Murphy admits he is happy the ground is being redeveloped.
"I have mixed emotions because there is a lot of history and tradition at the ground. But as a full-back I won't be sad to see it go," he said.
"The wind at Lansdowne is unique - it shifts and changes. As a full-back it's never nice to have high balls floating at you from every angle.
"It's time we moved on and it will be nice to play at the new Lansdowne if I ever get there."