DtheMack:All United matches are "must-win"....if we only won the games you quote we would be bottom of the League by Christmas...
Every game is worth potentially 3 points. We have seen years were the team that won the title has had a good record vs. other top 3 or 4 clubs, and years were they did not. Wasn't that long ago we won the title while losing both games to Liverpool who finished 2nd that season. So while obviously nobody likes losing to their rival like that, at the end of the season those two games ended up being unimportant in deciding who won the title.
So the key is always get as many points as you can no matter who you are playing.