The truth is out there ... and so is your data. And just because there are no virtual black helicopters following you doesn't mean somebody somewhere doesn't have a bead on who you are and what you are doing.

From buttinski bosses to spies and spooks, there are plenty of reasons to be, well, a little paranoid about the vulnerability of your data and the potential loss of your privacy. To help you gauge the appropriate level of hysteria, we've rated each threat on our Paranoia Meter, using a scale of 1 (Don't worry, be happy) to 5 (Be afraid, be very afraid). Though we've taken a lighthearted approach, concerns about data privacy are not all fun and games.

"You can look at 'paranoia' as just a good way of having a long horizon," says Jim Harper, director of information policy studies at the Cato Institute. "Incentives exist for data practices to be abused very badly in the future. Being paranoid about them today is being rational about protecting yourself tomorrow."

Here are the top 10 reasons you should be paranoid every time you power up your PC:

Reason No. 10: Hollywood wants to terminate you

No, the Recording Industry Association of America and the Motion Picture Association of America aren't spying on you. They've got people for that, specifically companies such as BayTSP and SafeMedia, which infiltrate peer-to-peer networks so they can record file swappers' IP addresses and the types and number of files they're sharing. An IP address isn't proof positive of your identity, but it's good enough for most civil suits -- unless, of course, it belongs to a dead person or someone who doesn't actually own a computer.

If you never visit p-to-p nets, you're probably safe. If you do, using anonymous IP networks, Web proxy services, or open Wi-Fi connections can make your identity much harder to trace, says Peter Eckersley, staff technologist for the Electronic Frontier Foundation.

"Aside from the huge, open p-to-p networks like Gnutella/LimeWire or eDonkey/eMule, many people share files with their friends on small-scale networks," Eckersley adds. "In those situations, copyright holders would have to send undercover agents to infiltrate those groups if they wanted to trace the participants."

Given the revenue at stake and the history of the players involved, if you're swapping tunes with a small circle of friends, be sure to keep your attorney's phone number handy, just in case.

Paranoia Meter: 2

Reason No. 9: You are your own worst enemy

Got a MySpace page? LinkedIn resume? Facebook profile?

When it comes to sharing personal data (sometimes a bit too personal), many people are their own worst enemy. Letting it all out online is fine, until the day of that big job interview when you're asked to explain how you ended up in that Geeks Gone Wild video.

Roughly one out of five employers look at social networks when making hiring decisions, according to a survey by Viadeo, a European business social network. And with the ongoing proliferation of the social networking phenomenon, that number is only likely to grow.

"In general, people should be more concerned about the image they portray in places like MySpace and Facebook," says Beth Givens, director of the Privacy Rights Clearinghouse. "More and more employers are searching them. Or one day you want to volunteer for an organization like Big Brothers or Big Sisters. You don't want to look like a drunk on the beach."

OK, fine, you're hot. But does the world have to know it? Consider being a little more anti-social.

Paranoia Meter: 2