BTW, regarding the question of why more folks aren't posting on this topic about taking their NSXs to the track - I think a lot of the posts here, and the material in the links provided here, cover a lot of good background information for the novice.
One thing I'd like to add, which DanO didn't exactly say in his excellent post above but sort of implied it, is this: When you're starting out, concentrate on learning and driving the line first, and not on driving as fast as you can. Then, as you learn the line and get consistent with it, you can add speed incrementally. If you try to drive fast before you have learned the line, you will have a much more difficult time.
One more comment: The basic principle in the line (as the fastest way around the track) is "maximum possible radius through the turns". As a result of this principle, you can drive the line faster than you can drive away from the line. Drive the line and you will find that you can often add speed. Drive away from the line and you often can't.