Against Heresies - Each book in its own file, with notes and links to contents, previous, next. Large file sizes. Book 1, for example, is 240K. - http://www.ccel.org/ccel/schaff/anf01.ix.ii.html
Adversus Haereses - No notes, but smaller file sizes, because each chapter has its own file. - http://www.newadvent.org/fathers/0103.htm