Network computer maker Sun Microsystems Inc. (SUNW) on Tuesday said it agreed to buy SeeBeyond Technology Corp. (SBYN), which makes software that stitches together disparate computer systems, for $387 million in cash.

Sun, which is trying to expand beyond the commoditized, workhorse machines it sells to run big corporate computer systems, said that the acquisition would give it a strong position in the $5 billion business integration market.

"We now jump right to the front of the business integration market," said Sun Chairman and Chief Executive Scott McNealy on a conference call.

Sun, which was a Wall Street darling in the heady Internet boom of the late nineties, has since seen the collapse of its stock price and revenue and profits fall. McNealy is now looking to reposition the company to move into faster-growing markets such as storage and Web services.

Under the agreement, Sun said it will pay $4.25 a share, representing a nearly 30 percent premium to SeeBeyond's closing stock price of $3.28 on Nasdaq on Monday.

The deal follows Sun's recently announced plans to acquire storage equipment maker Storage Technology Corp. (STK) for $4.1 billion. That deal boosts Sun presence in the fast-growing market for data storage. New regulations require companies store more accounting and health care information.

Sun and SeeBeyond had signed an agreement in October 2004 to market their products jointly. Sun will incorporate SeeBeyond's Integrated Composite Application Network software suite with its Java Enterprise System, an integrated collection of software that helps businesses run.

The combination will allow Sun to offer customers products that tie together their disparate external applications, such as payroll and others, the company said.

"We continue to see customers wanting a platform approach," said Sun President and Chief Operating Officer Jonathan Schwartz on the conference call, referring to customers' desire for more simplified and bundled technology offerings, rather than having to piece them together themselves.

Sun said it expects to complete the transaction in the next four-to-five months.

Shares of SeeBeyond, which had revenue of $167 million in the past 12 months, surged 30 percent to $4.27 on the Nasdaq.