(MONEY Magazine) – Betting with Bill Gates seems like a clever investing strategy. The richest man in America put $1 billion into Comcast, the fourth largest cable-television firm, in June 1997. Since that vote of confidence, cable-TV stocks have climbed some 50%. Gates' latest purchase is Firefly Network, an Internet security-software firm he bought in April. Here again, Gates may be onto something. Firms that safeguard data on the Net are already prime beneficiaries of the cyber bonanza. Research firm International Data Corp. expects the value of online commerce to reach $100 billion by 2001. But that will happen only if consumers are confident their credit-card numbers and other personal data are secure. As a result, the market for security software is growing 50% a year and is larger than the volume of commerce the software is protecting. CIBC Oppenheimer analyst Nicole Schmidt currently recommends two firms in that business: New Dimension Software (recent price: $27.50) and Memco Software ($29). --Duff McDonald

Gillette's new Mach3 razor may be a technological marvel, with its three blades, innovative pivoting head and aerodynamic handle. But how much will it add to the bottom line? Clearly, shareholders have high expectations--from its September low, the stock climbed 55% to a recent peak of $124. Gillette is going to have to sell a lot of razors, though, to justify that run. The company has spent some $750 million to develop the new razor and will have to shell out another $300 million over the next 18 months to market it. Even Gillette bulls concede that at best the Mach3 will help maintain--but not accelerate--the company's 17% annual growth rate of the past five years. Paine Webber analyst Andrew Shore figures that if the new razor grabs 20% of the market by 2000, it will contribute just 8% of Gillette's earnings that year. Nice work by the engineers, but those numbers won't support a 46 P/E the next time the market turns down. --Pablo Galarza

Where can you get a 6% yield--or even more--and 6% annual growth? Take a look at some of the natural gas master limited partnerships (MLPs) that have units trading on the New York Stock Exchange. These companies earn a comfortable return--mostly from pipelines that transport natural gas and natural gas liquids--and make regular distributions to partnership unit holders. And their profits are high enough to fund additional capital investments that keep distributions growing. Both Dain Rauscher analyst Mark Easterbrook and PaineWebber analyst Ronald Barone like Leviathan Gas Pipeline ($32.25, 6.5% yield) and Kinder Morgan Energy Partners ($36, 6.3%). One note: MLPs allow you to defer taxes on part of your distribution, which is great, but require you to file an additional tax form, which can be a pain. --D.M.

The Reader's Digest redesign sure has made the magazine look snappier. But does it signal the long-awaited turnaround at the troubled firm, whose $27 stock is down 50% from its December 1992 high? The company is trying hard. Along with the redesign, the company has halved its dividend to conserve cash and named a new chairman and CEO--Thomas O. Ryder from American Express. But it looks as though shareholders will have to wait a long time for the payoff. Some 80% of the company's profits come from its direct-mail operation, which uses extensive mailing lists to sell books, videos and CDs to 100 million people worldwide. Responses to promotional mailings--a good indicator of future profit trends--have been dropping for more than a year. --D.M.

Fund manager of the month: Why Heiko Thieme is delighted even though his fund is off 13%

You'd think manager Heiko Thieme of the American Heritage fund, last year's No. 1 performer, would be the only 55-year-old man in America not celebrating Pfizer's new impotence drug, Viagra. Thieme has 72% of the super-risky fund's assets in Senetek PLC, a British firm whose chief product is another impotence treatment, Invicorp, which requires injections (and is still awaiting government approval). But Thieme claims he's delighted, even though his fund is down 13% in '98. "Viagra's opened up the market," he says. We'll see. --Sarah Rose

Are Robertson Stephens fund managers about to take their money and run? When BankAmerica bought the firm in October, the managers signed deals that will pay them an estimated $50 million or more, on condition that they stay for three to four years. But now B of A's proposed merger with NationsBank could unlock those golden handcuffs. B of A has already put Robbie Stephens' investment banking division on the block because of overlap with NationsBank's Montgomery Securities; it hasn't yet decided what to do with the money-management division. Robertson Stephens fund group president Randy Hecht acknowledges that the managers' contracts contain change-of-control clauses but declines to comment on what might trigger them. Fund shareholders should be alert for developments that could lead to manager defections. --Scott Medintz