PSAT..... What type of grade do I need?

This is the US News & World Report's rankings of the best schools in the US: http://www.usnews.com/usnews/edu/college/rankings/rankindex_brief.php

If you want the premium (read: complete) version, it'll cost ya, but this does give some ideas on what's needed, particularly for upper-level schools. And, since you have some specific schools in mind, check out their websites.

Plus, remember that it's not just about scores. It's also about activities, need, your essay, diversity, that sort of thing. And, a PSAT is fine but it's really SATs and ACHs that are at issue when you're looking to be admitted to college. PSATs are something of an indicator of how you'll do on the SATs, plus the PSAT is used to determine the National Merit Scholarship Winners.