I think that no matter what Jack and co. did and will do in 1977 won't change the future. Everything they've done so far led to what we know as their past 3 years. However, in the present Locke is going to kill Jacob - whoever he is - and probably this will be the action that somehow changes everything, not what the others do in 1977 (as we already know they've failed).
Is it me or in the latest episode Richard was portrayed for the first time as someone who just follows the leader and don't have much clue? In 1977 he looked helpless and unsure about what they're going to do, in 2007 he actually expressed his mistrust in Locke's actions.
When I went to sleep last night I thought about the beginning of Season 3 where Ben kept Kate, Jack and Sawyer captive. He dressed Kate and took for breakfast, treated her like a lady. It means he remembered her as the one to save his life and maybe that was his way to thank her? And if he remembered and knew everything, why did he never kill Sayid? He knew that Sayid must become the man who shoots him and makes him the person he is, so Ben is there when Sayid's wife is buried and uses him in his plans, building Sayid's hatred and eventual attempt to kill him as a kid. And what about Juliet? Ben didn't bring her to the island just for her knowledge or his emotions, he knew she must be there to eventually become one of the people that saves his life.
The only thing I question is the fate of those who left the island in 1977. For now we know Sawyer, Kate and Juliet are in the submarine, but if they or anyone else made it to the real world, shouldn't they be in their 50s-60s in 2004-2007? Where are they now?