You're probably better off starting with Python 2.6. Python 3 is not seeing wide use yet, and the Python community is still revolving around Python 2.6, so that's what you'll be able to get lots of help with. IIRC Dive into Python is written for people who already have experience in programming, so it might be a bit hard if you don't, but there quite a few books about learning how to program with Python.

You can use many languages to learn, but I'm pretty sure Python is indeed the best choice for a first language.