Open forum: How bad is it really? And any other credit questions you're dying to ask

Pop quiz, hotshot: If you're concerned about your credit, what should you do? Close your credit cards or get new ones? Stop using your existing cards? Swap out for a charge card?

Here's what I'd do: Call John Ulzheimer. He used to work at Equifax, one of the biggest credit reporting agencies, and at Fair Isaac, the folks who developed the credit score. Those black-box models that determine whether you can get a loan, an apartment, sometimes even a job? To John, they're nothing more than entry-level Sudoku. Now, as president of consumer education for Credit.com, he's letting the sun shine in.

So if you've got questions about credit scores, credit cards, loans, the effects of a tiny little bill you let slide, now's your chance. Ask in the comments below by mid-day tomorrow (Thursday), and we'll get answers from John by Friday.