Swedishfish, was the war in Vietnam really "won" by Vietnam? They managed to avoid defeat, yes, but I don't see a vietnameese flag hanging from the white house... Get my point?
North Vietnam was pushing for unification through war, with America standing in the way. Not only did they manage to create one Vietnam under Communist rule, they also managed to make the US withdraw, a victory in itself. You don't really think, had the Tet Offensive never occur, or had the US manage to push and take Hanoi, that the public opinion would stay anti-war do you? Through an offensive defense, the N. Vietnamese managed to break America's will to fight. They won.