How Much Does a Fiction Writer Make?

Ever hear the joke, "What's the difference between X and a large pizza?" (where X is: a drummer, a ski instructor, or in this case could be a writer.)The answer to the joke, while germane, follows at the end of the blog.
For the non-J.K. Rowling writer, it doesn't appear to be the best-paying gig. As in, it really doesn't pay much at all. Damn the movies for convincing me that a writer's life is all tea and crumpets, fine dining, and a writing desk overlooking (fill in dreamscape here). I really was hoping for a job in which I could work in my pajamas. I guess that's still a possibility if I were to get a job writing reviews of mattresses for a mattress-maker.
For the fantasy job of writing fiction from the comfort of my writing desk overlooking the valley below and Mt. Rainier and Mt. Adams in the distance, and doing this in my pajamas, I should probably expect to earn enough to pay for the coffee that I consume while writing. Maybe. A person could pad that income by writing magazine articles, speaking for hire, or in my case, maintaining a full-time job. Basically, hustling. This article gives a good run-down of what to expect as a fiction writer: http://answers.yahoo.com/question/index?qid=20070310135839AAbSlno
And I think that this author's candid post on the topic does a lot to inform prospective writers: http://laurasalas.livejournal.com/109047.html
So, if A) you're thinking "I want to be a writer and eat tea and crumpets whilst writing at my writing desk overlooking (x)" or B) you're thinking "when she hits it big I hope she remembers me" then I have news for you -- expect both to be a long time coming. That's really not enough to dissuade me from writing, and hopefully won't discourage you either. My goal is to just keep on writing. Earning money from that would be great, maybe I'd use it to buy a nice writing desk.
Now that we have that answered, the answer to the joke "What is the difference between a writer and a large pizza?" is: "The pizza can feed a family of four."Next blog topic, "What's your day job?"