The whole talk is great but here are a few quotes I think are particularly important (although that's a bit like saying we'll just focus on the eyes of the Mona Lisa while ignoring the whole painting).
"There is something in us, at least in too many of us, that particularly fails to forgive and forget earlier mistakes in life—either mistakes we ourselves have made or the mistakes of others. That is not good. It is not Christian. It stands in terrible opposition to the grandeur and majesty of the Atonement of Christ. To be tied to earlier mistakes—our own or other people’s—is the worst kind of wallowing in the past from which we are called to cease and desist...."
"When something is over and done with, when it has been repented of as fully as it can be repented of, when life has moved on as it should and a lot of other wonderfully good things have happened since then, it is not right to go back and open up some ancient wound that the Son of God Himself died trying to heal..." (emphasis added).
"Faith is for the future. Faith builds on the past but never longs to stay there. Faith trusts that God has great things in store for each of us and that Christ truly is the 'high priest of good things to come.'"
He also threw in one good joke: "Now, as a passing comment, I don’t know whether Lot’s wife, like Miniver, was a drinker, but if she was, she certainly ended up with plenty of salt for her pretzels."
Again, I think this talk is one of the best I've heard (it reminds me a bit of Elder Holland's talk An High Priest of Good Things to Come, which was given during the October 1999 General Conference). It's available in the New BYU Speeches podcast I linked to earlier. It's also available on the BYU Speeches website with a free PDF, free html, and a free MP3 of the talk.