How do higher ranked colleges look at SAT scores?

I have wanted to go to either UC Berkeley or Cornell University ever since freshman year. Currently i have a 3.875 GPA (uw), while taking 2 AP cles and 2 honors cles, next year i will take 4 AP cles. I am involved in 2 varsity sports per year + a mock trial team (which i am captain of), and have a couple leadership roles like student government a youth leadership seminar and 100 hours so far in community service this year. I havent taken the SAT yet, but i have taken an SAT cl which allowed us to take a PSAT. My scores was a 2000, a 800w 600m and 600cr. I will be taking the test in the spring, and plan to improve my math a critical reading by atleast 100 points each. Basically what i want to know is; does my 800 writing really matter and what are my chances of getting into either of these schools?