As a Realtor & as a mother of 2 teenagers, I understand the value of a good school. As I am sure you have figured out, the real estate values surrounding good schools tend to be the highest. Just look at Cupertino, Palo Alto, Saratoga & Los Gatos. In San Jose, Almaden Valley consistently has the highest scoring schools, from elementary up to Leland High School, and this area has strong resale value. Leigh HS, Pioneer HS, and Evergreen HS are all very good as well.
However, please remember that the score only tells part of the story. If the home is in an area where the economic demographics vary widely, the scores may be more a reflection of the wide variety of students attending than the quality of the school & teachers. Many kids in high school do not take these STAR tests seriously, since there is no benefit in doing well on this test for the students.
So, do your homework. Visit the schools. Talk to teachers & parents. Look at the graduation rates & percentage of students going onto universities. And don't forget the extra-curricular activities. If your child excels in drama, art, music, sports, various schools have very strong programs in these important areas. Here is to a well-rounded child.