The battle to make computer processors run faster and do more never ends--even if most of the users can't say what, exactly, they'll use that extra speed for. What's new is that the latest round of the competition sees not Intel but its competitor AMD in the lead.

AMD's K6-2 and K6-III processors have offered advantages in price and grabbed business from Intel at the bottom and middle of the market, but with its new Athlon processor the company aims to eat Intel's dinner instead of its lunch. This chip, introduced in 500, 550, 600 and 650 MHz versions, can zip through complex instructions faster than the Pentium III. Its "Enhanced 3DNow!" instructions further improve multimedia, speech recognition, video encoding and streaming applications--if that software has been rewritten to take advantage of these shortcuts, as is the case with the Pentium III's own "SSE" instructions. Finally, a 2-megabyte Level 2 cache (a block of memory where data is copied for easy retrieval) four times that of the Pentium III's and the industry's first 200 MHz system bus (which transports data among the processor and other components) allow for quicker communication among all components.

In our tests, the Athlon outperformed Intel's fastest Pentium III chip decisively in every industry-standard home and business benchmark test available. The benefits of this speed are most apparent in high-end applications: Digitally enhancing photos, working with 3-D graphics and editing home videos all go faster, while computer games run smoother and look more realistic. If you're not doing those kinds of things, mainstream Windows applications, like word processing, spreadsheets and personal-finance software should still perform better--but the difference is a lot harder to see when it comes down to cycling through a spell-check a few seconds faster.

So what's all this to you? If you're looking for the fastest number-crunching around, it's hard to beat the Athlon now (and a 700 MHz version supposed to arrive by the end of the year). But Intel is readying its own upgrades, with a redesigned Pentium III projected to run at 700 and 733 MHz set to arrive in the next few weeks. Over the next several months, Intel will pump up speeds even further when it begins to bundle Pentium IIIs with radically new chipset (the brains of the motherboard) and memory technologies.

And in the meantime, Intel is countering with price cuts and favorable deals for major computer manufacturers. This is bad for AMD, but good for you inasmuch as it lowers the final cost of any given computer.

The cheapest Athlon system we could find comes from direct seller CyberMax ($1,350 for a 500 MHz Athlon rig, including a 19-inch monitor), with other moderately priced setups available in stores from Compaq and IBM. But there's no need to rush into stores just yet. For one thing, Rich Partridge, research director for DH Brown Associates, suggests waiting a few weeks to see what impact the earthquake in Taiwan (where AMD gets all its motherboards) will have on manufacturing; also, see if the skyrocketing price of memory will stabilize. And AMD's own fortunes bear watching; its recent gains with the K6 lines have been hampered by untimely delays in the supply chain, lackluster support by major computer manufacturers and a negligible presence in the lucrative business market. If AMD fumbles significantly, analysts expect it to either fold or become prime acquisition bait.

Whichever side you're on, Partridge offers a good rule of thumb: "Most people can comfortably buy two clock speeds lower than the highest speed available to reap the greatest value." So if you're looking for great performance, but don't need the absolute newest processor, look at a 500 MHz Athlon or Pentium III system. Find yourself more budget-minded, or requiring only enough power to run Word, balance your checkbook and cruise the Internet? Stick with an Intel Celeron or an AMD K6-2/K6-III. You'll find these units for less than a grand, and the processor you get will keep on working regardless of what happens to AMD or Intel.