Those areas included moving Oracle databases and WebSphere application servers to Linux, where "the cost savings are comical," Seager said. Meanwhile, Red Hat pointed out that switching out Windows servers already running on Intel hardware would lead to tiny cost savings at best.

Most of Key's servers are Hewlett-Packard two- or four-way boxes, models such as the 360, 380 or 585 running Intel processors, Seager said. They typically start at just $3,000, rather than $30,000 for a Sun Sparc-based server. That price difference won over Key Bank executives who were initially hesitant about the move.

"Telling them Linux was cool or the new thing didn't translate very well," Seager said. "Saying it saved x percent of our budget translated very well."

Key has spent only about $1 million on Linux servers in the past year and a half, a fraction of what it would have otherwise spent on upgrades to new proprietary Unix servers.

Featurewise, Seager only needed Red Hat to be "on par" with Unix platforms, with reliability the most important factor. So far, he said, it hasn't disappointed. Key also runs internal monitoring and system management applications on Linux, as well as Web and network servers.