Should I take the IB Diploma or A Levels if I wish to study at Oxford University?

I am hoping to study combined History and English at Oxford University for entry in 2011/2012. The IB Diploma excites me, as I an academically advantageous student. On the IB, I would take English, History and German at Higher Level, and Biology/Physics, Psychology/Art and Design and Maths at Standard Level. Please help!