It depends, I was more involved with my daughter when we read the Hello World book and it was really nice because some odd things about computers were explained

It depends, I was more involved with my daughter when we read the Hello World book and it was really nice because some odd things about computers were explained in simple language, and the character of the kid which questions everything is really fit for this type of book. Also, there were lots of small games with different mechanics. Python for Kids is really good also, has a intro about the Python language which feels more focused than the other book and it has a chapter about drawing with a turtle, as I did with LOGO many years ago! ... Python for Kids also has plenty of notes about running it on Windows, Mac OS X and Ubuntu so you'd be fine on any OS you have. I think you should try both, but the best order would be to finish Hello World first and Python For Kids second.