Dunham advocates a monthly cleaning of servers, including the fans. "That's one of the biggest things people neglect, even in clean environments," he says. Backup servers take the load while technicians perform the system maintenance.

DiDio says older servers can also serve as "cold" backups for front-line servers during downtime. In the case of Windows servers, she says, new volume-licensing agreements allow the use of cold backup servers for redundancy without incurring extra costs.

There is a downside to keeping equipment longer. Most companies rotate a percentage of systems every year, so a five-year rotation might mean more models to manage, says Locker. "If I replace /[computers] every three years, at any point in time, I have three models I am supporting," he says. "If I replace every five years, I have five models."

As computers get older, parts may be harder to find. "No vendor commits to providing replacement parts beyond five years," says Gartner's Enck. Over time, the price for those older, slower spare parts can actually increase.

Meanwhile, the cost of new equipment continues to drop. "In 2005, companies can purchase a midrange server configuration equipped with two to four processors that provides 40 percent to 50 percent more processing power, better reliability and scalability, for 50 percent to 60 percent less than what companies paid for a single processor machine that they purchased in 1999," says DiDio.