Would you have any recommendations for a relatively easy to learn programming environment within Windows for this process?
Visual C# (free from Microsoft, for non-commercial purposes) is my choice for reading from/writing to the serial port (also known as communicating with the Arduino).
Of course, it isn't the serial port that you want to talk to.
But, C# is great for internet scripting, too.
Each machine has a seperate Arduino, card, Wifi, etc.
So, the fact that there are 5 of them is irrelevant, isn't it?