Corporate Tax Rates

This article on Yahoo Finance about the tax rates paid by the largest US firms is a pretty big eye opener. These tax numbers are astounding. Why, when the country's budget is in such disarray and public sector budgets are in dire straits, are these very profitable companies paying so little in taxes?

I know the theory is that they should be using the lower tax rates/excess income for hiring new employees, R&D, and expanding operations, but is this really happening? It seems quite a few firms are expanding operations by buying rivals, but that only seems to further monopolize companies and, usually, leads to them laying people off that might be redundant when the companies merge. Even though the article has Boeing claiming that they hired 9,000 workers, it does not say how many they might have laid off in previous years.

Many of these private sector gains have been more than offset by public sector losses due to, you guessed it, lower tax receipts. Is it really a net positive when a company gets a tax break for hiring a few employees when, in doing so, the break causes public sector workers to get laid off?

Is this really what was intended by lawmakers when they created these tax breaks? Do you believe more tax breaks will cause companies to begin hiring again? What do you think should be done about corporate taxes?