The thing about the HBO series is that I honestly think that if it goes into season 4, 5, 6, etc it will pass the books by. George Martin is a agonizingly slow writer, I am not sure if he is a victim of constant rewrites or if he just has so much on the go that he does not have the time to spend writing as much as he would like but I honestly think that eventually the series will pass the books by and George will have to divulge to the series the directions he is taking the story before the books come out.
This would be a real shame because while I love the series, I like the books even more, and if I was to learn what happens in the story from the series first I am not sure if I would like the series as much as I do now...