I know about the Man Utd vs Leeds Utd rivalry, yes - the fans link it back to the "rose wars" and so on. But I guess it could be said that the United vs Arsenal rivalry is pretty much the opposite - that it is mainly on the pitch. For the fans, it is Liverpool, Leeds and City. For the players and Ferguson, it seems like Arsenal is the team to beat. At least it was like that a few years ago. I don't think the games between them this season were that tense. Perhaps it's due to the fact that many of the players involved in the controversies have left?
United have sold Ruud van Nistelrooy, and Roy Keane has retired. Arsenal have sold Patrick Vieira, Martin Keown has also retired. Add to this the fact that Gary Neville has been out all season with an injury, that Thierry Henry is at Barcelona and Phil Neville is at Goodison. That takes away a lot of heat ... Of course, the fact that United and Arsenal have fought for the title many times the last 10 years whereas Spurs haven't finished ahead of the Gunners once in the same period of time, certainly makes the rivalry between United and Arsenal more tense. However, I guess most older fans of Arsenal still feel it more painful losing to Spurs than to United? I mean, the North London rivalry has historical roots all the way back to the foundation of the clubs ...
On a general note, I guess whenever a traditional rivalry involves two clubs where one is much more successful than the other one (Arsenal vs Spurs, United vs City, Liverpool vs Everton) I guess the less successful club takes this rivalry more seriously. It's not that painful losing to your neighbours when you win the league ...