Earth out of resources in 50 years

An article in the morning paper here in Seattle outlined a report by the Environmental Resource Council outlining the "ecological footprint" of various countries and concludes that at present rates of growth, energy and resource usage, we will need a second Earth type planet to accomodate us.
The idea of the ecological footprint, for those of you who might not have heard of it, is to trace the consumption of a given individual (on average), or a company or a whole country, then determine the amount of earth's resources used to produce the items consumed, i.e. X number of acres of grain to produce the bread eaten, X pounds of pesticides used to protect the grain, X amount of petroleum used to fertilize the grain and harvest it, and bring it to market, etc, etc.
Not surprisingly, the US leads the world, followed by Australia, Sweden and Western Europe. China and India account for a huge amount of new consumption, especially of oil.
The authors raise another issue: we tend to be worried about how long the oil will last, but they pose the question differently: "how long can the earth sustain the burning of fossil fuel?" We may still have oil in the ground but be unable to use it because of global warming or other ecological problems.
The article wasn't terribly optimistic and some of its premises were debated by folks not necessarily representing big oil, who argued that the authors failed to consider advances in technology. While there have been essays like this throughout history, most of which did fail to account for changes in technology (Malthus's failure or inability to foresee the huge advances in agriculture that made it possible to feed vastly more people than he imagined), the basis of the article seems sound to me.
The main reason I bought a Prius was to lessen my impact on the environment. In an ideal world, there would be adequate public transportation to eliminate the need for a car in the first place. I tell people who ask, that Prius is primarly designed to reduce environmental damage, not save gas.
My partner and I have decided to bite the bullet and convert our house to solar, which we'll integrate into the Seattle City Light power we use. Pricey, but I think it makes sense. If any of you are interested in this, I'd be happy to appraise you of our progress. We are getting a second estimate on Oct 23rd, and will probably start work shortly thereafter to get the system up and running before the sun comes back.
Bob