I am an experienced programmer, and found that I was much much happier learning how to do AVR controller development using command line tools. For some people, the Arduino path can be a good one, especially if you can get the GUI installed and running properly. If you choose to use certain Arduino shields and want to simply leverage code that has already been written for you, going with the Arduino GUI and Arduino compatible boards may be an excellent choice.
"Arduino" is a name for both a project and a family of little boards that have at their core an Atmel AVR microcontroller. One of the best things about them is that they are fairly cheap. You can buy a basic Arduino for less than $40.
It is important to understand the Arduino culture. They were designed to appeal to non-tech savvy people (like artists). They are programmed using "sketches" (which are essentially mongrel C++ programs). Software development is done using the Java based arduino gui, which tries to hide as many details as possible.
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