The money will be spent in the "next couple years" on tasks such as training customers, tuning their software for mainframes and helping them migrate computing infrastructure, said Jim Stallings, who in January took over as head of the mainframe group.

"When you have a mainframe in your infrastructure, you understand its attributes. If you haven't been exposed to that, it's very different," Stallings said. "We're going to spend a bunch of money helping them."

Mainframes are lauded even by competitors for their reliability and heavy-duty communication abilities. But the machines don't come cheap--the new System z9 Business Class has lowered the starting price to $100,000--and there are abundant competitors running Unix, Linux and Windows that administrators are more likely to learn about.

Prime candidates for mainframe purchases are customers running servers from Sun Microsystems and Hewlett-Packard, Stallings said. Those competitors have their own counterpoint prepared, though. "IBM mainframe customers are moving to HP because the cost of the mainframe no longer makes business sense," said Mark Hudson, vice president of marketing for HP's Enterprise Storage and Servers group, arguing that the costs are lower for the relatively mainstream Intel processor technology in its Integrity server lines.

IBM has growth hopes for the mainframe, however. Stallings pointed to three main thrusts to make that growth a reality.

First, Big Blue expects to benefit from special-purpose mainframe hardware--IFL for running Linux, zIIP for running IBM's DB2 database software, and zAAP for running Java software. Buying that hardware frees up more expensive processing capacity for general-purpose tasks.

And IBM plans more such "specialty engines," Stallings said, citing search, regulatory compliance and security as possible areas.

Second, IBM is expanding into new regions where mainframes are scarce. That includes Russia, China and India, Stallings said. The new $100,000 machine is key to this effort, he said: "We're at a price point now you can afford."

The third expansion area is security. IBM wants mainframes to be a "security hub" for the center of customers' encrypted communications, he said.