HEWLETT-PACKARD Co has agreed to buy the security software provider ArcSight for about US$1.5 billion, the company said yesterday as it extends a recent spree of acquisitions.

The deal is part of a strategy begun under former CEO Mark Hurd, with the company looking to grow outside the low-margin personal computer market. It agreed to buy the data-storage maker 3Par for US$2.07 billion just a few weeks ago after a bidding war with rival Dell Inc.

The acquisitions have continued even after Hurd's departure. He was forced to resign last month after an internal investigation found that he faked expense reports to cover up a relationship with an outside contractor. HP is suing Hurd, who has denied the allegations, to keep him out of a job at rival Oracle Corp.

ArcSight Inc, based in Cupertino, California, helps organizations keep tabs on the data flowing through their computer networks and analyze it for signs of hacking, theft or fraud. Its revenue in the most recent fiscal year came to about US$181 million.

Yesterday, HP said it would offer ArcSight stockholders US$43.50 per share in cash.