Aristotle's original texts.
The texts of Aristotle's various works that you'll find on the web are
of varying quality. Some excellent scholarly work has been done over the
last twenty years or so on most of the Aristotelian corpus, so that
recently published translations and editions are generally much more accurate
and readable than the earlier, more famous works (which much of the
older professoriate still cherishes for various reasons that aren't relevant
to a beginning philosopher). All this means that many of the best translations
are not in the public domain, and hence not on the web (at least not legally,
except for snippets here and there). For instance, my favorite translation
of the Nicomachaen Ethics is by Terence Irwin (Hackett, 1985), which
you won't find on the web (fortunately, it is in paperback). So my advice
is to use web-based texts for convenience but not for that Big Paper that
you might be writing someday for an Aristotelian seminar or any other sort
of specialized course. When you get to that point, seek advice, since at
this time there is no single edition of Aristotle's collected works that
wins the prize of being the "definitive edition." (Here is a challenge for
anyone who finds the history of art important. Can you identify the great Renaissance
artist who drew the sketch of Aristotle shown here? Hint: He was Italian!)
Secondary works. Once again, the secondary sources listed by
Palmer at the end of his chapter are all quite good, though I don't know
why he listed Christopher Biffle's Guided Tour as a primary
source (it's much more valuable for what it says about Aristotle).
I think that most students will find Timothy Robinson's Aristotle in
Outline (Hackett, 1995) useful, since as its title indicates it offers
an overview of Aristotle's entire system of thought, but does not "dumb
it down." One of my own favorite secondary works is W.F.R. Hardie's Aristotle's
Ethical Theory (Oxford, 1968). Even though the book is rather technical,
a beginning student can go to its excellent index, find the topic
he or she is investigating, and then read that section with profit without
having to wad through the whole volume.