"We have spoken as a group about how important it is for us to win on Saturday," said the Wales coach, who has called up James Hook, Gavin Henson, Lloyd Burns and Luke Charteris.
"If we are going to be serious contenders in this World Cup, we need to send out a message that we are good enough to beat England at home and do that next week as well (against Argentina).
"I don't want us going into a World Cup with people thinking that Wales are good enough to win games, but for that to be a surprise or an upset. We need the win this weekend - it's as simple as that.
"We have the toughest pool at the tournament, and in less than a month's time we will be facing South Africa in our opening match.
"It is vitally important we go into that match with the sound of Welsh fans ringing in our ears, fans who have cheered us on to victories in the final two matches of our warm-up campaign against England and Argentina."
Charteris and Burns get their chance after impressing as substitutes last weekend while Hook replaces the unlucky Morgan Stoddart who broke his leg at Twickenham while a lot of interest will be placed on Gavin Henson who is attempting to make his first World Cup squad in the highly competitive Welsh midfield.
"There is a lot of competition in that position," admitted Gatland. Gavin summed it up perfectly himself in that he needs to have a good performance."
Rhys Priestland is one player hoping to build on his stellar performance from last weekend. In a losing side, the young man stood up to the plate after being given just 10mins notice that he would be replacing Stephen Jones at fly half after the veteran tweaked a calf muscle in the warm-up.
"We were impressed with Rhys and felt he deserved another chance," said Gatland.
"For a young player to be told 10 minutes before kick-off he was moving positions, and to handle the pressure that he did and play as well as he did under that pressure away from home, we were impressed with him.
"We wanted to try to keep continuity from last week and build on it.,We expect perhaps a lot of similarity from last week (with England) - strong at scrummage time, strong in driving lineouts. It is going to be a tough encounter for us.."
Wales James Hook; George North, Jamie Roberts, Gavin Henson, Shane Williams; Rhys Priestland, Mike Phillips; Paul James, Lloyd Burns, Craig Mitchell, Luke Charteris, Alun Wyn Jones, Dan Lydiate, Sam Warburton (Capt), Toby Faletau.
Replacements: Huw Bennett, Ryan Bevington, Josh Turnbull, Justin Tipuric, Tavis Knoyle, Scott Williams, Aled Brew.
England: Ben Foden; Chris Ashton; Mike Tindall (Capt), Shontayne Hape, Mark Cueto, Toby Flood, Richard Wigglesworth; Alex Corbisiero, Steve Thompson, Dan Cole, L Deacon, Courtney Lawes, T Wood, H Fourie, N Easter.
Replacements: Lee Mears, Matt Stevens, Tom Palmer, James Haskell, Danny Care, Charlie Hodgson, Matt Banahan
Referee: Alain Rolland (Ireland).
* Close to 70,000 tickets been sold which already delivers a record crowd for any summer rugby international at the venue.
Tickets for Wales v England are available at £30 for adults and £15 for children via the ticket hotline 02920 230130 until 5.30pm today and to personal callers at Ticketline and Cardiff Rugby Club from 9am until kick-off on matchday.