If you're an international college applicant, you are probably unfamiliar with the format of the SAT exam.
The SAT is normally required for all applicants at most schools. Internationals are required to write the SAT as well as Americans. However, colleges do understand that international students may not be familiar with the SAT (with the exception of internationals studying in American schools abroad) and thus may not do as well as their American counterparts. This is especially true for applicants whose native language is not English.
Do colleges give some leniency to international students with regard to the SAT? The answer depends on which college is in question. Some colleges may have a policy whereby if an international applicant scores 2000 or higher, then SATs are out of the way. Many others have no clear policies though. At highly selective institutions, the difference in weightage for Americans and internationals may be small.
In my opinion, even as an international, you should strive to do as well as you can on the SAT. There're many books that are dedicated to SAT preparation on the market; just browse the shelves of any well-stocked bookstore. College Board itself has produced several excellent preparation materials that you should use as your preparation materials. If you can afford it, you can even join one of the many prep courses available.
Why is it important? First of all, international students with high critical reading scores have considerable advantages (hook) over other international applicants. As there will be many internationals who willl probably not have scores in the high 700s in the critical reading section, scoring well earns you some advantage over the others. It shows your willingness to learn something totally new to you.
Besides, some universities such as Northwestern and Virginia will waive the TOEFL requirement if your criticial reading score is above a certain threshold, as an acknowledgment of your English proficiency. Therefore, doing well on the SAT can only work in your favor.