Best is awfully subjective, but I can make a few suggestions.
To start with, the main Python site actually has some excellent tutorials, as well as all of the documentation references for the language.
The Dive Into Python online text is a good one if you are already familiar with at least one other language, but it isn't really for beginners. The same can be said for the well-regarded Thinking in Python - good if you already are an experienced programmer, not so good for a rank novice. However, Eckel does mention a website called A Bite of Python as a good starting place; I haven't looked at it enough to give a recommendation, but from what I've seen it seems pretty good. I would recommend the 3.0 branch rather than the 2.6 branch, as you're better off learning the new version of the language from the start.
Think Python is a free text on the subject, an update of the venerable How to Think Like A Computer Scientist series.If it is anything like it's predecessor, it is probably a good choice for someone with no programming background at all.
I'm sure there are many others around, if you look.