Let's imagine that The Motley Fool gave you $100,000 to invest in your favorite stock two decades ago. We agreed to split the winnings after 20 years. Why? Because you're smart, you look like a million bucks, and you've got no detectable personal hygiene issues. We like you. We believe in you.

The year is 1988. A hundred thousand bucks has your nerves on edge, so you pop a Michael Bolton cassette into your Walkman (from before he went adult-contemporary) and cruise to the local cinema to catch the matinee of Bruce Willis' new flick, Die Hard. Three hours later, kicking past a strip mall of Thom McAn, Arthur Treacher's Fish & Chips, Bradlees, and Crazy Eddie, you have an idea.

You'll ask Gramps for his favorite stock, then you'll ask your cousin Marilyn Meeker for hers. Gramps was a banker for 41 years. Marilyn's getting a business degree. You'll get two different perspectives. Good plan.

Two roads diverged
Over finger sandwiches and Canada Dry on the patio of your grandfather's country estate, he raises a crooked index finger to the sky and says simply, "Eastman Kodak (NYSE:EK). The stock's a stalwart. It's up 150% for me over the past 20 years. A nice, conservative pick."

A few days later, hammering away at a Galaga machine at the local arcade, your cousin rattles on about a small-cap stock. "It's a new issue," she says. "Dell (NASDAQ:DELL). It makes computers that are compatible with IBM (NYSE:IBM) PCs. If you've got 20 years, go with a solid small company like Dell. It's in a great industry and its founder and CEO owns a ton of stock."

After a few hours of reflection, you rotary-dial your Motley Fool contact with this directive: "For the next 20 years, I say put that $100,000 into _______."

Which?

The 20-year mark
Since 1988, Eastman Kodak is actually down about 50%, for a miserable average yearly loss of 3.4%. Against that, Dell is up 100 times in value. With Kodak, your $100,000 has turned into just over $50,000. With Dell, it's swelled to $10 million. That's the difference between thousands and millions for long-term investors.

At Motley Fool Hidden Gems, we search for these multimillion-dollar opportunities by analyzing promising small-cap growth stories like Ctrip.com (NASDAQ:CTRP) and Natus Medical (NASDAQ:BABY), while avoiding overgrown giants like General Motors (NYSE:GM) and AT&T (NYSE:T).

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This article, written by Motley Fool co-founder Tom Gardner, was originally published on Jan. 3, 2006. It has been updated by Dan Caplinger, who doesn't own shares of the companies mentioned. Ctrip.com and Natus Medical are Hidden Gems recommendations. Dell is a Motley Fool Inside Value pick. The Fool is investors writing for investors.