Kevin Murray, CIO of domestic brokerage and personal lines for American International Group (AIG), had a mainframe full of fat-client legacy applications. He just trashed it in favor of newly written thin-client Java and XML applications.

Dan Roberts, CIO of the PMI Group, a mortgage insurance company, is in the middle of Web-enabling his back-office legacy systems, a project he anticipates will take up to three years. However, he says it’s "absolutely necessary" if his company is going to keep up with product development and customer demands.

Maria Fitzpatrick, CIO of PacifiCare Health Systems, just decided to get away from the multiple OpenVMS and Unix programs scattered across her company’s business units, and upgrade to a single Web-enabled platform. The project is part of a major effort to redesign PacifiCare’s corporate strategy by unifying business processes across all units.

The list, long now, will get longer. Every day thousands of enterprises rely on decades-old applications written in obsolete programming languages that, along with the systems on which they reside, are no longer supported by the application’s creators?whoever they were and wherever they may be.

So why don’t CIOs just pull the plug on these ancient applications?

"If it was that easy to get off these systems, most CIOs would have done it already," says Dale Vecchio, research director of application development for Stamford, Conn.-based Gartner.

"The only way I’ll address renovating my legacy systems is if they stop enabling the business," says John White, vice president of IT at Parker Hannifin, a Cleveland-based manufacturer. "My barometer is the ROI," he says.

While White’s rule of thumb is widely held, more and more business executives are coming to grips with the fact that the Internet has placed demands on companies and computing systems?such as real-time order processing and managing high-bandwidth demands?that most legacy applications just can’t handle. CIOs know this better than anyone else. But right now would be the worst time for an organization to begin a major infrastructure face-lift, wouldn’t it? The economy is in clampdown mode. Enterprises are struggling to find cash for the most basic projects. Only the nuttiest CIO would argue for spending money on infrastructure, and only the most irresponsible CEO would approve the expenditure. Right?

Actually, not right. In fact, spending money to keep legacy applications going is a mistake. Assigning personnel to keep legacy applications running is a big mistake. Making business plans based on legacy applications is an enormous mistake.

Despite all apparent evidence to the contrary, right now is the ideal time to either pull the plug (which would be ideal) or overhaul legacy applications. And a whole roster of major American enterprises are seizing this opportunity to get a jump on their competitors by modernizing (connecting their legacy system to a Web front end) or migrating their legacy systems to new thin-client-based Web systems.