Until then, Superdome--which can run Windows and Unix applications simultaneously--will serve as the transitional platform. "IBM and Sun couldn't do that," Parnell says. Plus, he says, the new Superdome should provide a fourfold to fivefold increase in performance compared with its predecessor, the 9000 V-class server.

While Unix rules the high-end server market, it will soon face competition from Windows running on Intel. Microsoft has begun introducing software that promises the improved reliability needed to land a place in corporate data centers, and Intel's 64-bit Itanium chip promises to provide inexpensive horsepower to drive the Windows environment.

IT managers such as Scott Sullivan, VP for technology and operations at Homestore.com Inc., say that approach is the best way to build a high-end IT infrastructure that's relatively quick, easy, and inexpensive to scale when business demands it. Sullivan manages hundreds of Wintel servers that let him easily keep up with growth--the Westlake Village, Calif., home-improvement and real estate company has seen the average number of unique visitors per month increase 87% from a year ago to 6.7 million in the first quarter. Sullivan sees systems based on Intel's 64-bit Itanium chip as the most cost-effective way to power new broadband applications such as real-time virtual home modeling. Dell expects to sell a fully configured version of its PowerEdge 7150 server with four 800-MHz Itanium processors for $40,000 to $45,000. That's less than half the list price of Sun's Enterprise 3500 server, with four 400-MHz UltraSparc II modules.

Price is one reason Gafar Lawal, director of architecture at Merrill Lynch & Co.'s U.S. Private Client group, may add Itanium servers to boost headroom on the group's customer database. Lawal also says adding Intel servers is easier than other options. "We want to be able to just add machines rather than redo our entire infrastructure," he says. "The initial culture we had was that if you have anything mission-critical, you put it on Unix. A large part of our IT shop now believes we can put mission-critical apps on Wintel."

Merrill Lynch isn't alone in that assessment. The Aberdeen Group predicts that 42% of worldwide server revenue will flow from Itanium-based systems by 2005.

But don't count out the original high-end machine: the mainframe. While some users are migrating off big iron, others say new mainframe software and configuration capabilities actually simplify infrastructure management and cut costs. Paul Watkins, network analyst at consumer-goods manufacturer Newell Rubbermaid Inc. in Freeport, Ill., is thrilled with the company's decision to monitor its network from an IBM mainframe. Rubbermaid used to outsource the management of 190 routers and switches for up to $40 each per month. To eliminate that expense, IT staffers at the company created a partition on a mainframe generally used for order processing and accounting and installed the Red Hat Linux operating system and the open-source MRTG program for pooling and monitoring the routers and switches.

Rubbermaid considered running the systems-management applications on Unix servers and, as an interim step, tried to manage the devices with a single Windows NT server. But the mainframe was more efficient. "I used to poll half of the devices in an hour," Watkins says. "Now I poll them all in six minutes, and the system is generating thousands of files a second."

Bypassing a new Unix system saved at least $200,000 in up-front costs and even more in ongoing management, Watkins says. And he doesn't think a Unix system could beat the mainframe's performance. "It screams," he says. The mainframe also handles all the order processing and accounting for the $8 billion company. As for the network monitoring, "we use very little system capacity, we have a gigabyte of data rewritten every six minutes, tech support can change the resources whenever they need, and we've had no unscheduled downtime since the fall," he says. "I attribute that to the power of the mainframe."

IBM isn't sitting still with its mainframe technology, either. Its new zOS with Linux lets customers run both mainframe applications and heavy-duty Windows or Unix applications on a single machine. In the coming months, IT managers will be able to manage the systems from off-site and over the Internet. IBM also has added new self-healing and self-management functions to the mainframe, including a feature called Prism that lets administrators set up workload triggers in advance. When a database starts to hit its peak load as user activity increases, Prism on zOS moves more processing power and memory to handle the workload. "No operator has to know anything," says John Morris, VP of marketing and sales for IBM's eServer zSeries. "Unix customers end up with server farms because they have to throw another server at their problems."

Still, some IT managers prefer Unix servers. United Airlines Corp. in Elk Grove, Ill., has 2,300 mainframe Mips on the floor. To plan flights according to passenger loads, the airline is deploying a data warehouse on IBM's massively parallel processing SP system on RS/6000 servers. The high-end parallel AIX-based architecture helps United parse out 100 terabytes of legacy data.

United plans to cut over to the new data warehouse next month. Airline officials say scalability is why IBM got the business. "I couldn't find a single multiterabyte data warehouse on an HP symmetric multiprocessing server running Oracle," says Raj Sivakumar, research and development director at United. Databases and applications running across a massively parallel processing system like the SP are split up over isolated nodes. With a symmetric multiprocessing system, all resources are shared. "For large-scale data warehouse success, the system must scale," Sivakumar says. "There's no linear scalability in symmetric multiprocessing, and Oracle wasn't going to cut it."

For some IT managers, however, service and support are more important than hardware specs. "There's nothing an UltraSparc processor does on its own that makes money for us," says BellSouth's Liddell. "The support you get from the platform vendor and the apps they support determine the operating system you go for." Sun has helped many times to work out problems with software vendors, Liddell says, and also has installed extra capacity over a weekend.

Meinz of General Mills used the same service and support yardsticks to choose HP. "It's more important to me to have a partner and not bounce from vendor to vendor because of a hot box," he says.

Sara Garrison, senior VP for technology at Visa USA Inc. in San Francisco, says service is what makes her a loyal Sun customer. Visa is building a new payment network based on a Sun cluster running an Oracle database, backed by a Symmetrix storage system from EMC Corp. The credit-card company wants to run all payments on the Visa network to all end devices. Garrison is building the cluster to process 10,000 messages per second. "The issue with the cluster isn't the boxes, because they'll continue to improve as everyone is racing to be the best," she says. "They become somewhat of a commodity, and we're comfortable with the price/performance from Sun." What's more important to Garrison is that Sun always has service people at the ready. "Visa is everywhere you want to be," she says, "so our systems have to be up all the time."