Yeh but armour was not perfected in them times... they didnt have great alloys like we do now.
The House of Valois was eventually victorious over that of the Plantagenets.
Although England won most of the battles, it was France who actually won the war as they profited the most from the ordeal. France gained nationalism, something vital to an empire that wants to sustain its independence. During the war, France was made up of states each ruled by a Duke with their own interests at hand. Late in the war they realised the importance to unite in order to push the English from their lands. England lost because they had insufficient numbers occupying the garrisons they conqured and this allowed the French to slowly wear them down, along with the help of great leaders such as Bertrand du Guesclin and Joan of Arc. The English were eventually repelled to the Pale of Calais. But technically the English won the war 1337-1453!
Read more:
http://wiki.answers.com/Q/Who_won_the_Hundred_Years'_War#ixzz1PA4qB5Tk