Help on getting in to a US university from an English education???

[Von Lipwig]

Hey, so I am English and a few years back I had to take part in some random experiment where they had us take a SAT Reasoning Test. We didn't know we were taking it until we got into the exam room, so there was no preparation at all, so I'm pretty sure it's probably not so good, but I was thinking of applying to a uni in US and wanted to know what the results mean and what a good result would be...I will probably retake them in October if I decide to go to college over there to give me time to swat up and that

What I got in 2005 (Nov):
Critical Reading : 610
Mathematics : 780
Writing (composite) : 640
Writing (multiple choice) : 60
Essay : 10

I did have a look at a few websites to see how to figure out the total score, but am not sure if I add essay and multiple choice to that or not? And then is it out of 2400?? Any help you can give is much appreciated..
Sorry...I am looking at MIT to do engineering or physics...
in England I have already done a degree in engineering mathematics, but it doesn't transfer as it is a two year distance learning one, however I have A Levels in mathematics, advanced mathematics, physics and french all at good grades, and I got into 6 good English universities to study physics/engineering.