How hard is it to score a perfect score on the SAT?

Well, I am an entering sopre (high school) for the 09-10 school year. School starts Monday, and I am more prepared than ever. Sopres generally take the PSAT test, and I was wondering what is it all about? How hard is it (generally speaking)? Should I take a SAT prep course? WHat are some tips on the PSAT/SAT?