Yes, colleges will accept either ACT or SAT results whenever they are taken.  Some students take these two test as 10th graders, but most students take the PSAT- the preliminary SAT at that grade.  In fact, some states actually pay for all 10th graders to take the PSAT.
 
I strongly encourage you to take the PSAT as a 10th grader but in answer to your question, those scores count if you want to submit them to a college when you begin applying for college as a senior.