For three miserable months in 1993, I shared a house in Oakland, California, with a bunch of college dropouts and recent graduates who were in an awful band. Since then, I've tried to forget everything about the place, including the address. But I found out that a host of online investigation services know all about that dark period--and lots of other details about my personal life. And they can probably dig up lots of information about you, too.

The Web is rife with spam and banner ads that promise to "get the scoop on anybody." And the background check business has been booming since September 11. Many employers run checks on job applicants, and some landlords demand a background check if you want to rent an apartment or house.

I hired some online gumshoes to research me. In the end, a lot of the personal data they dug up and reported was either misleading or simply incorrect: One set of digital detectives indicated that I might have been convicted of a felony in Texas (sorry, wrong guy). That kind of mistake can cost you a job, a home, or a significant other.

I hired three services: ChoicePoint.net, USSearch.com, and WhoisHe.com. The sites' prices range from $20 to $100, depending on how much information you want them to unearth.

All three services found my previous addresses, some going back ten years. USSearch's query also turned up the names of the owners of buildings where I lived, and the names, addresses, and phone numbers of former neighbors (most of whom I had never met).

ChoicePoint found a hit for "Drew Brandt" on a Texas database of felony convicts, but it thoughtfully noted that the possible ID doesn't "match all necessary criteria"--that is, the service's investigators couldn't say for sure whether I'm an ex-con (which, by the way, I'm not).

I also discovered that, in several cases, clerical errors introduced mistakes into my history. One search associated my Social Security number with someone named Bobby Williams.

How can you ensure that your personal information isn't up for sale? In some cases, unfortunately, you can't do much. Marriages, mortgages, and other public records will always be accessible. You have a little more control over private transactions. Request that the three major credit reporting agencies ( Equifax, Experian, and TransUnion) restrict access to your credit report to companies you do business with, and check their reports for errors. Contact your bank, your insurance company, and your investment company, and ask them not to share your data with third parties, partners, or subsidiaries. Protecting your data today could save you a mountain of trouble tomorrow.

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