This is all set before Alien, it's basically the story of how that ship ended up on LV426. I was wondering (worried really) about the whole tech aspect as it does initially look like they are running around much better equipped (which was bound to be a problem with having CGI and such now) but what we have to remember is the Nostromo was a mining ship - this ship exploring and finding the space craft might well be a scientific/military vessel and more likely to have advanced tech. I'm sure there will be a decent way of explaining it anyway, it's not the sort of thing Ridley would overlook.
They tend not to though, It is just evolution of what we have in our time now and the tech to make movies.
10 years ago we would not think we would have something like the ipad so readily available for example and the stuff we will have in 5 years time - OMG!
That and what you can do in movies now means you can just get your vision down more. I bet when he Made Alien he was like - can we o this, can we do hat and they got what they could. He can now get his vision down on paper.
Most directors just avoid the temptation to go back and mess with their old movies, others buy the rights to old movies and do remakes or some directors do their own remake or re-envisioning. One of them (Lucas) decides to constantly mess with his movies.
