Sun Microsystems and Fujitsu Ltd. want corporate users to see the two companies as being joined at the hip when it comes to their jointly developed Sparc Enterprise server line. But that only applies to engineering and product development. Otherwise, the two vendors will be competing for customers.

Users who meet separately with salespeople from Sun and Fujitsu about the new Unix servers, which were announced in New York this week, may hear different proposals regarding service and support and possibly hardware pricing as well.

The agreement between the two companies allows for competitive offers to customers, said John Fowler, executive vice president of Sun's systems group.

Richard McCormack, senior vice president of marketing at Fujitsu Computer Systems said he expects customers buying the Sparc Enterprise systems -- which can cost into the millions of dollars at the high end -- to base their purchasing decisions on the entire range of products offered by the two vendors.

"We [compete] today and will continue to do that," McCormack said.

It remains to be seen, though, whether many Sun customers in the U.S. will call Fujitsu sales reps to hear a rival pitch for a product that is similar to one sold by Sun itself. Sun dominates the U.S. market for Sparc-based systems, while Fujitsu's strongest regions for sales are Asia and Europe.

Sun and Fujitsu have collaborated for many years, and officials at both companies said that their joint involvement in the new server line is for the long term. Sparc Enterprise customers wouldn't expect anything less, according to Fowler.

"Companies at this level expect to be taken care of for years to come if they buy these products," he said.

Sun's future commitment to the Sparc Enterprise line has been questioned by some analysts, who see the multithreaded, multicore Rock processor that the company is developing as a potential replacement for the Fujitsu-built Sparc64 VI dual-core processor used in the new systems.

Rock will support up to 16 processor cores per chip, and systems based on the device are expected to be ready for release near the end of next year.

Those machines will be aimed at the same kind of memory-intensive back-office and high-performance computing workloads that the Sparc Enterprise machines can handle.

Sun executives have been reluctant to explain how the two server lines will fit together or to discuss future product development directions in general prior to the announcement with Fujitsu.

But Fowler said that he thinks the servers built around Rock "will end up being an alternative product" to the jointly developed systems.

And the two companies said that they plan to offer a quad-core Sparc64 processor in the Sparc Enterprise line during 2008.

Corporate users may not move quickly to adopt Rock-based hardware because of its advanced technology, said Vernon Turner, an analyst at Framingham, Mass.-based IDC who was at Tuesday's announcement.