We use a quarter of the @ 84 million barrels consumed daily on the planet. The Chinese are catching up rapidly. In 2002 the usage number was 79 million bbls daily. The rate of usage growth is unprecedented. While it is true that there are generations worth of reserves in the ground, the means to exploit them are not keeping up with the growth in demand. There is a dearth of both qualified engineers and the raw materiel they would need to build new infrastructure facilities to meet the rapidly rising demand.
Saudi Arabia produces @ 10.5 million bbls daily. They are the only "super power" in the oil industry. Their stated goal is 12.5 million by 2009. That is an additional 2 million bbls per day in four years. Nice, but the demand is growing at a rate that is exponentially higher. They say they can get to 15 million eventually but the demand might very well get there years before the ability to meet it can...that is the problem, not how much oil is in the ground.
And, there is no way to verify what the Saudis claim. They use their own engineers to calculate capacity and resevoirs but will not permit any outside party to even peek at their books. All the Saudis have is oil. It is not in their interest to paint a less than glowing picture of the near and long term.
There is an oddly archaic tendancy on this forum to lump all negative predictions into the same chicken-little category. I think that attitude is dangerously smug. Peak oil questions are not global warming questions. It is not "conservative" to dismiss either without thorough examination, it is just plain dumb.