Hewlett-Packard is bringing the fastest Pentium III notebook chip to its slimmest laptops by blowing off a little hot air.

Today HP will unveil a redesigned version of its slim OmniBook 900 containing a 500-MHz Pentium III processor, currently Intel_s fastest notebook chip. The portable will also come with a 13-inch screen for the first time, according to company executives. Larger screens and faster processors are part of an industry-wide effort to close the performance gap between notebooks and desktops. Notebooks and notebook components generally carry higher profit margins than desktop PCs, making them more attractive to manufacturers. The design elements of portables also allow companies greater opportunities to differentiate their products. The ability to fit the high-end chip into the OmniBook 900 largely comes down to techniques for dissipating the heat that is generated by the processor and other components, said Mark Jourlait, director of worldwide market development for the mobile computing division at HP. Many of the sweeping curves and chic design features that come on modern notebooks are there to facilitate air flow, he added. Wireless networking services from AT&T will be offered as an option. Prices will be around $3,300 for the new OmniBook 900s, depending on configuration. One of the next signposts in notebook evolution will occur Jan. 18 when Intel releases new Pentium III notebook chips with "SpeedStep" technology. SpeedStep will allow a processor to run faster when plugged in than when running on battery power. A 600-MHz notebook Pentium III, coming in January, will run at close to 500 MHz when unplugged. The change is important because it will allow notebook makers to incorporate faster chips without compromising battery life, Intel executives and analysts have said. AMD will incorporate a similar technology, called Gemini, into its notebook chips in 2000. Despite these developments, consumers will likely see relatively stable prices and periodic difficulties in getting notebooks because of a lingering display shortage, several executives have said.