New IBM computer raises pressure.

IBM is selling a powerful new business computer that fills an important gap in its product line and steps up pressure on rival sellers of machines that use the Unix operating system, a competitor to Microsoft_s Windows program. IBM_s move is a counterpoint to a recent flurry of publicity for Sun Microsystems Inc._s popular line of Unix computers. Hewlett-Packard Corp. also is a major maker of Unix computers.IBM plans to unveil its new S80 computer on Monday, which it says outperforms rivals_ comparable products, able to handle more than 40,000 computing operations a second. The new model in IBM_s RS 6000 line costs $290,000 and uses up to 24 microprocessors made with copper, which performs better than the traditional aluminum used in chips. IBM, also a maker of computer chips, was the first major company to switch to copper. IBM officials said the new Unix machine is aimed at helping businesses handle heavy-duty corporate tasks, such as running Web sites, managing networks of desktop computers and processing millions of transactions. IBM_s announcement comes after Sun took the spotlight last week by unveiling a bare-bones machine that never needs a software upgrade and is far simpler than conventional desktop computers. Customers need to buy a powerful Sun computer in order to run a network of the simple machines. A week earlier, Sun said it bought a small maker of office productivity programs and intends to distribute the applications for free over the Internet, to anyone with a Web browser. That way, users don_t have to load bulky and expensive programs directly onto their computer desktop.