When is enough, enough?

I have a problem with ALWAYS getting my kids what they want year round, but I am even worse at Christmas. I have them make a list around Thanksgiving, Jakson decided too a bit earlier this year, and I head off with list and ads in hand around mid-night on Black Friday. And I shop non stop until Christmas eve. I never think they have enough. Though I get just about every reasonable thing on their lists and then from my own list I've made for them. The harder the item is to find, the more I resolve to find it. This year, it was Guitar Hero 3 for the X box 360. I couldn't find it anywhere, not at any stores, or online. So I made up for it with other things. Well, someone my sister works with found it and had her call me to see if I still wanted it. Duh, of course I do. So my problem now is, giving it to Jakson for Christmas, so he's not disappointed with Santa, or wait 2 weeks and give it to him on his birthday? Jared is no help, he is almost worse then me when it comes to giving them what they want. He's says give it for Christmas, but now I'm stuck on what to get him for his b-day. I am so bad, I just can't help myself.