Rather then reading reference manuals, I found I was picking up C/C++ faster by just reading as many of the existing example sketches as possible. Many are very simple and great for first learning, later one can even open up and read the many arduino 'core' library files to see how low level programming is used to manipulate the AVRs many registers. Make no mistake, C/C++ can be a write only language if the programmer wants to be very terse and obscure on how they perform tasks, but it's also possible to write and understand very simple and clear functions, the Arduino platform was based on developing easy to use and understand functions like digitalRead(pin#); rather then the low level commands needed to read a I/O port register and pick out the bit of interest.
With your background you will have little problem picking it up. And the AVR type applications are so down to earth most times, you don't get burdened by having to understand all the Windows API before you can even start writing simple programs.
Good luck and enjoy your Arduino, better then sliced bread.
Lefty