From what the admissions people told me, they consider anything above a 650 the "competitive range." If you are above that range, they will cursorily look over your SAT scores. Anything under that, however, they will look into deeper to see why you scored so low.
Your SAT scores are amazing. I have a 1470 out of 1600; 800 on math and 700 on writing, and my college counselors told me that it's in the range that MIT looks for.
They have a whole page on admissions statistics here:
MIT Admissions: Admissions Statistics
You're in the range, don't worry about your SAT's anymore and get working on those essays! =D