Also, I find myself in a dilemma. I bought the first book and I'm going to read it, no problem. But I'm wondering whether I should watch season two before reading the second book. I think if I read all the books first the series will be ruined for me as my expectations might be too high. Whereas watch the series first won't impact the books at all, actually it might make me appreciate the books even more having all the details and characters fleshed out more.
when I first read the books I thought they have to make a tv series out of this!! Now that they have, I can't wait for every season and episode to come out... to see these books come to life and not just in my imagination.
But I can't tell you what to do... or what would bring you the most satisfaction. I can tell you though that for one, television brings so much to the forefront and also visually depicts many facets that are only casually described in the books. HOWEVER, the show misses out on a lot of subtext as well as the internal thoughts and dreams of many characters... there is so much foreshadowing in the book and so many hints as to what is going to happen that you only pick up on a second or even third read.
For example that theory you put above... (which kinda spoilery eh) it is barely, barely hinted at in the show if at all... however if you are aware of it... even in the first book alone, you see so much evidence for it. But it is so well done that most people do not see it, without a hint or being spoiled online.
Personally... and when you complete the first three books you will see... I think it is the theory that makes the most sense.
From Rhaegar's prophecies, to the tales of the Tournament at Harrenhal and the Knight of the Laughing Tree and Ned's dreams and memories of the Tower of Joy. It is clear.
Some ppl even say GRRM will change it, because ppl figure it out or never reveal the secret for spite. Hopefully we will find out.