I used the Saxon curriculum from Algebra to Algebra II, Advanced Mathematics (Which has a big focus on Trigonometry), and Calculus (which delves into derivatives, differential equations, and integrals that are necessary for upper-level math courses), and Physics (self-explanatory). I found that Saxon Calculus prepared me WONDERFULLY for my freshman college-level Calculus I class I'm taking right now.
As has been said, Saxon stresses repetition on the problem sets; expect to find problems from 30 lessons back in some sets (which I found to be a wonderful addition). Plus, the solution manuals are an important resource, as they go through the problem solving step-by-step.
You won't regret using the Saxon curriculum. It sure helped me out (my little 12-year old brother's using the Algebra book as we speak).
Random fact: The derivative of an object's velocity equals its acceleration. ;)
We're considering Saxon for our oldest son now. He will turn 11 soon. I've been using a variety of inexpensive books and materials, but I guess it's time to start him on one math curriculum that he can follow into the high school level. And so many homeschoolers recommend Saxon.