In one important way the Internet is like an endless succession of one-night stands: You have to protect yourself. You must ask the right questions, think before you hop into just any Web site, and always be ready with the protective latex of good software.

Here are some of the biggest online dangers, along with ways to protect yourself.

Viruses

Viruses have plagued computer users since the days of DOS, but the Internet has allowed them to spread like bootleg "Lord of the Rings" DVDs. In the old days, we never had to worry about mail worms or any of the most prevalent and dangerous infection found today: the hoax virus.

For instance, the previous paragraph infected your computer with the very dangerous hoax virus, FalsePositive. The only way to remove FalsePositive from your computer is to format your hard drive, throw away your Windows CD-ROM, and move to Kentucky.

To protect yourself from future viruses, get a good antivirus program like AntiMatter AntiVirus. AntiMatter works in the background, asking every new file and e-mail message if it contains a virus. Should a file or message answer "Yes," AntiMatter will push your computer into another dimension.

Spam

It's getting harder and harder to separate your spam from those occasional pieces of legitimate e-mail, thanks to the forged From addresses, deceitful Subjects, and other spammer's scams for tricking you into opening their missives. The e-mail may appear to be from your mother, and the subject next Sunday's dinner, but the contents are still about enlarging your penis. (Important note: If the message about enlarging your penis really is from your mother, contact a psychiatrist immediately.)

The logic behind this deception is simple: If you do everything humanly possible to avoid spam, but are nevertheless tricked into opening a message, you're much more likely to trust the sender with your credit card number.

The solution to your spam problem is a filtering program like FlimFlam Software's NoCannedMeat, which can remove all e-mail from your mother. And NoCannedMeat is free! All you have to do is give FlimFlam Software your e-mail address and not ask them how they'll use it.

Hackers

There are people trying desperately to get onto your computer, and I don't mean your kids. These villains are looking for Social Security numbers, passwords, overdue library books--anything to help them steal your identity, pretend to be you, and replace humanity with pod people.

These unscrupulous hackers use all sorts of tricks to gain illicit access to your PC. They sneak in via virtual back doors. They climb in through Windows. At the right time of year they even slide down your chimney.

What can you do about it? Install EastBlock Software's Berlin FireWall. When an illicit program tries to move between your PC and the Internet, Berlin FireWall shoots to kill. According to EastBlock Software, no program has ever successfully gotten through Berlin FireWall, no program would ever want to get through Berlin FireWall, and those that have wanted to and succeeded are worthless traitors.

Pop-up ads

You can't just load a single Web page anymore. Click on one link and eight unwanted pages pop up. All you may want to do is read some college paper on the effect of quantum mechanics on the works of Rudyard Kipling, but the text is obscured by animated ads for fast cars and loose cigarettes, exploding photographs of naked protestants, and rousing marches by John Phillip Sousa.

And new Web pages pop up as quickly as you close the old ones. To get a handle on these ads, download and install FearMuchWare's $20 shareware program FlopPopBopCop. This Web monitor stops 40 percent of pop-ups, along with 80 percent of legitimate Web pages.

If that's not enough for you, spend the extra $10 to get SuperMopPopSlopShop. This one hides all pop-ups behind useful and interesting ads.

Cookies

Every Web site leaves a little something behind on your hard drive. For historical reasons these digital souvenirs are called "cookies" rather than "doggy d0o."

Most cookies are benign, as are most tumors. But some are designed to track your every move for the benefit of people who want to sell you things. For instance, a cookie from an automotive site might note that in three days time you visited sites about football, heavy metal music, and beer. As a result, you'll get increased spam for feminine hygiene products.

Amazingly enough, you don't have to buy any special software to protect yourself from cookies. Just set your browser to not accept cookies without your explicit permission. Soon you will be clicking "No" eight or nine times for every Web page, breaking you once and for all of the Internet habit and solving all of these problems.