This is so exciting. But I am completely lost. From my first reading I get this card is similar to an Arduino. So here goes my first question:

Can I use an old Arduino card for this purpose, with these instructions? I bought one once, and almost never used it. I did some childish tests with a breadboard.

Second question: Can I use a computer instead of a usb card like these? Why is this type of hardtware required? Or is it just that it is cheaper than a computer?

Thank you very much for the article and for any comments on simpler stuff I can read, more elementary things to get started.

And excuse the silly questions :-)