here ain't no such thing as a free lunch, so the aphorism goes. Such is the case with NetZero, a year-old Westlake Village, Calif.-based company that offers free Internet access in return for beaming ads into your browser. I didn't have to shell out any cash, but I began paying for my account the day I signed up.

Granted, activation was a relatively simple process. I went to the company's Web site, clicked on the download link, and within 10 minutes the program was on my desktop. (The company will mail you the Windows-only software on disk for $7, but it takes two weeks to arrive.) After choosing a user name and password, however, my dialup connection kept dropping in mid-login.

A call to the company yielded a recording advising me that I could make a long-distance call to technical support during business hours, but my best bet was NetZero's Internet-based problem-reporting service.

Because I already have a functioning, non-free Internet account, I was able to follow this suggestion. After selecting my problem from a series of codes, I sent off my complaint via e-mail and -- voila -- hours later a reply explained how to fix the problem.

Before I could gain access to the free service, though, I had to answer about 40 pointed, personal questions. NetZero makes its money, or tries to, by selling advertising, and advertisers want to make surgical strikes if they're going to fork over funds to an upstart like NetZero. They want to know what I like so they can sell it to me.

After spending 15 minutes sharing details about my annual income, family members and spending habits, I finally logged on to find a user-friendly home page, complete with an efficient search engine. Also flashing before me was a four-inch-by-one-inch box filled with ads from -- what else? -- my favorite companies, such as Amazon.com and Staples. When I tried to close the ad box, I was informed that I'd be disconnected from the NetZero service.

Clever strategy. Surely, I was clever, too. I thought I could outsmart the ads by ignoring them. So I began surfing away. Every three minutes, it seemed, I had to move NetZero's ad banner so I could read what was on my screen. Each time I moved the banner, I read the ad. The longer I was online, the more I was seduced by the power of suggestion. Eventually, I buckled. I clicked on Amazon's ad banner one minute, and the next I purchased a CD.

After that, my will power got stronger, and I resisted other pitches. But the ads are omnipresent, and in moments of weakness I have rationalized taking a break from my usual Webwork to shop online. This should come as good news to marketing mavens questioning whether they should buy ad space on NetZero and other free Internet-access companies.

NetZero's future is a different question, as other firms offering free Internet access, such as San Jose, Calif.-based @Bigger.net, have cratered. The key to success remains the eyeballs of customers, without enough of which ad revenue won't cover operating costs. Analysts estimate an access provider needs 100,000 users to be attractive to advertisers; NetZero reports 1.68 million registered users as of Aug. 31.

All of whom face that blinking ad box every time they log on. Yes, you'll save $10 or $20 a month, but using NetZero is like being stuck with a TV that only broadcasts commercials -- and you can't change the channel.