Why is SICP generally preferred over HtDP?
Kaizyn: SICP and HtDP have different audiences.  HtDP was designed for people who know nothing about computer programming, particularly students who would not be pursuing a degree in computer science.  SICP was used in a first CS course.  Because they both use Scheme, they're complimentary.  If you are starting out trying programming for the first time, then HtDP will certainly be a better choice.  When you finish it, you should proceed to read SICP, followed by Concepts, Techniques, and Models of Computer Programming.