Scott McNealy experienced a rare moment of humility on stage at Comdex in November. Speaking before several thousand of the show's attendees, Sun's chairman and chief executive officer admitted he had made a mistake in underestimating the strength of Intel Corp.'s IA-32 instruction set.

"We whiffed. I wish a heck of a long time ago we'd done the strategy we did with Intel," he said, "That low end x86 product line is now the fastest-growing part of our computer product line in the data center."

McNealy is not alone in underrating the longevity of IA-32, on which Intel's Xeon workstation and server chips are based, among others. Five years ago it seemed the entire IT industry was counting on Intel's 32-bit line to start fizzling out by 2004, to be replaced by Intel's new family of 64-bit processors, called Itanium.

That has not come to pass, and this week IDC lowered its estimate for sales of Itanium systems. The research company expects Itanium sales to hit $7.5 billion in 2007, down from its previous prediction of $8.7 billion.

And though Intel executives say they still expect Itanium sales to surpass IA-32-based Xeon volumes sometime near the middle of this decade, the company's 32-bit Xeon line appears to have a long life ahead of it.

"We think there's a lot of runway with Xeon," said Tom Bradicich, IBM Corp.'s chief technology officer for eServer xSeries. "We think Intel has done an excellent job with it."

IBM plans to ship a 32-processor version of its eServer x445 Xeon system this year, and in 2005 it will complete the next generation of its Enterprise X-Architecture (EXA) chipset, which forms the basis of its xSeries line of IA-32 systems. The new chipset will give IBM the capability to build even larger SMP (symmetric multiprocessing) systems for Xeon. "The architecture that we've established could actually go beyond 64-way," he said.

But does anyone want to buy 32-bit big iron?

Dell Inc. is cool to the idea. Last year it dropped plans to ship an eight-way Xeon system. "Xeon is just such a powerful platform that you don't need to add more and more processors in a single box," said Wendy Giever, a Dell spokeswoman. "People don't want to buy a big server and then figure out how to add more applications."

In fact, the only vendor currently selling 32-way Xeon systems is Unisys Corp., which claims to have sold only about 300 of its ES7000 servers in 32-processor configurations.

"Anything above four-way Xeon is a relatively niche market," said Gordon Haff, an analyst with Illuminata Inc., a Nashua, New Hampshire-based industry research firm. "The market for these kind of really big systems is really not increasing," he said.

Xeon's 32-bit architecture also limits the amount of memory that can be attached to a large SMP machine, said Haff. Sixty-four-bit chips like Itanium or UltraSparc can support far more memory than the 64G bytes available to 32-bit systems, he said. Because of this, and due to the fact that the individual applications running on 64-bit systems can also access much more memory than their 32-bit counterparts, IA-32 will only ever have limited appeal in the data center, Haff said.

While IBM's Bradicich concedes that 64-bit systems may have more appeal for database and mathematical- or security-intensive computing, he believes that large-scale 32-bit systems may gain traction as a platform for consolidating certain types of applications.

Big iron Xeon servers are working out for Helmut Porcher, the director of operations and systems software with TIES, a non-profit organization based in St. Paul, Minnesota, that provides information technology services to local school districts.