I think you'll agree that a big part of the investment battle during a period of triple-digit market flip-flops involves layering upside potential upon a solid base of downside protection.

That being the case, my inclination is to point again to a couple of related big-cap names that offer reasonable P/Es, along with at least their share of growth potential. The pair, Deere (NYSE: DE) and Caterpillar (NYSE: CAT), are in the middle of several global trends that could make latching onto their shares a profitable exercise.

Deere, for instance, has been benefited by a combination of agricultural strength -- some of it related to the production of ethanol -- and a weak dollar that's boosting sales abroad. The company, which manufactures all manner of agricultural and forestry equipment, much of which it sells abroad, carries a  P/E approaching 16 times for the fiscal year that ended in October. But with per-share earnings expected to increase by about 18% year over year, the P/E for the next year slides to about 13.4 times. Also worth noting is that the company's shares have risen almost 50% in the past year.

Caterpillar's shares have increased slightly less than 16% from a year ago, but have improved nearly 23% from their low thus far in 2008. The company, which makes an array of construction and mining machinery, along with diesel and natural gas engines, trades at about a forward 13 times multiple on the basis of its expected 2008 earnings. Like Deere, it is also benefiting from  industrialization abroad.

But given that its earnings are expected to grow by nearly 13% next year, the 2009 P/E is closer to just 11.6 times. And the company's beta of just 1.05 indicates that it won't hit you with valuation loop-de-loops in excess of those already being performed by the market.

There are, of course, other vehicles for accessing the strength of the machinery and industrial sector. For instance, companies like Manitowoc (NYSE: MTW), Terex (NYSE: TEX), Dover (NYSE: DOV), and Gardner Denver (NYSE: GDI) all have performed nicely relative to the market thus far in the still-new 2008.

So if you're like me, you're apt to be somewhat queasy about the economy and, consequently, about the market's ability to regain a degree of stability in the near term. On that basis, I find stocks like those mentioned above to be wonderfully medicinal in calming my jangled nerves.

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Fool contributor David Lee Smith does occasionally don a green Deere T-shirt but doesn't own shares in any of the companies mentioned. He does welcome your comments or questions. The Fool has a disclosure policy.