Does pornography = adultery?

I'm guessing most evangelicals will answer "yes" to the question: Does pornography equal adultery? (Although if you disagree, please share your thoughts below.) And I think that's right—but there's an excellent article over at The Atlantic this month about the topic which you should read even if you think you know the answer. It's by Ross Douthat (who is quickly becoming one of my favorite culture-commentators), and takes that seemingly straightforward moral question and unpacks it to reveal a lot of related questions about how our society understands pornography (please note: article contains frank language and subject matter). Questions like:

• Does it make a practical difference (in our everyday lives, marriages, or relationships) if we consider pornography a form of adultery, rather than "just" another sin?
• Is pornography ever something to be tolerated as an unpleasant but unavoidable "fix" for out-of-control sexual appetites? If pornography "safely" redirects sexual impulses that might otherwise go somewhere dangerous or illegal... does that make it less immoral?

Douthat (who does reference Jesus' famous warning about lust and adultery) suggests that pornography definitely exists on the "spectrum of adultery"—not as blatant or harmful as other forms of adultery, but something more serious than people like to admit. And current trends and technologies are making the distinction between pornography and adultery blurrier:

If it’s cheating on your wife to watch while another woman performs sexually in front of you, then why isn’t it cheating to watch while the same sort of spectacle unfolds on your laptop or TV? Isn’t the man who uses hard-core pornography already betraying his wife, whether or not the habit leads to anything worse? (The same goes, of course, for a wife betraying her husband—the arguments in this essay should be assumed to apply as well to the small minority of women who use porn.) [...]
This isn’t to say the distinction between hiring a prostitute and shelling out for online porn doesn’t matter; in moral issues, every distinction matters. But if you approach infidelity as a continuum of betrayal rather than an either/or proposition, then the Internet era has ratcheted the experience of pornography much closer to adultery than I suspect most porn users would like to admit.

This is an intensely personal subject, so I'm hesitant to ask you to relate your personal thoughts or experiences. But going just by the sobering statistics, this isn't an academic question for the majority of us. Do you consider pornography a betrayal of marriage vows? A harmless little vice? Does it matter?