I can 'bypass' the first problem by copying the entire stylesheet to blank new one, renaming it 'ie.css' and simply changing the right <div>'s right position to 10px.
However this makes no logical sense! Surely a 10px page margin + a 1px border = 11px for the right position??? How does IE interpret it as 10px when it manages to correctly render the left <div> which is also 11px???