A friend of mine has told me more than once how dangerous file sharing software is. I didn’t pay much attention because I don’t download music, so it didn’t make much of an impression on me. Sometimes I have to see it to believe it, but after what I was this morning, I’m a believer.

There was a segment on The Today Show this morning that featured a New York state family with two teenage girls who frequently downloaded and shared free music using the family’s PC. It’s such a common thing to do, the parents never made the association when their $2,000 federal income tax return was electronically intercepted and stolen last year.

Identity theft prevention expert and LifeLock CEO Todd Davis likened having those file sharing software programs on your computer to leaving the keys in an unlocked car … with the windows down.

Natalie Morales did some checking of her own and found that with that software she was able to find the family’s income tax forms online (think: Social Security numbers, dates of birth, bank account numbers, retirement account numbers …). Even more frightening, the files containing the family’s tax forms were found in four foreign countries, including Nigeria and Poland, known centers of organized identity theft rings.

Then she went a step further and, in the state of New York alone, was able to find 25,000 student loan applications and 600,000 credit reports.