FYI

that is not Arduino code... that's regular C on an AVR chip...

hello
I'm one of the creators of Arduino.

The language is c++, we just hide a couple of the most "scary" elements to beginners (mostly the includes at the beginning of the code)

anything you write after that is c/c++

"They essentially defined their entire language in a couple of pages." actually a lot of people would find this appealing...

if you don't like the IDE you can use a makefile to compile the code

m

Disclaimer: I invented arduino (along with my friends)

Arduino in the UK is 18.51 including VAT and it's much easier to use than that USB board. Also that Velleman kit is just an IO extension for your computer while arduino was born to make standalone objects.
As far as the book I would recommend Practical Electronics for Inventors, the title is a bit lame but it helps beginners more thans the Horowitz.

PS: An Arduino book is in the making....