My advice: find out if your targeted universities will accept the ACT (
http://www.actstudent.org/). Almost all big and small schools will, sometimes with a conversion table to turn it into an SAT score. I took both the ACT and the "old" SAT (the 1600pt one) in Fall 2004, and my ACT score, once converted to a SAT score, gained 280 points (to the 1500s).
The ACT and SAT are really quite different, and I much preferred the ACT. While the SAT tended to test on things you *knew* (analogies, vocabulary, etc.), the ACT seemed to test your *ability* to learn. For example, the ACT had a "science" section, where you would be presented with some kind of science-y report, complete with graphs and fairly dense language. You would then be given some questions requiring you to interpret the graphs and draw some kind of conclusions from the report. The reports were real, but about things like DNA traits and river pollution, and were far beyond the knowledge level of most high schoolers, so the test was on how well you could interpret a subject that was completely foreign (but in a familiar format).
So--if at all possible, try taking the ACT. You might not do any better, but if the SAT seems evil beyond your taste, it might be a nice break regardless.
**--All of my experiences are based on the SAT and ACT as of two years ago. While the SAT has changed substantially, I don't believe that the ACT has changed much, except for the (mostly) required addition of a writing portion. Also, I've had a pretty eventful two years, so my memory may be hazy and not fully correct.
