Thanks for the encouragement. I suppose I should have said that not reinventing the wheel makes perfect sense for knowledgeable programmers who are trying to get work done in real time. But I also see this advice all the time given to beginners (in beginner's books, in tutorials for newbies, etc.). That's the context I had in mind above.

As for other languages, I was planning to work through SICP this summer. From what I can tell, it is an outstanding introduction to programming full stop.