The Top 500 list of the world's fastest supercomputers has been updated. It looks like Intel (NASDAQ:INTC) made some serious headway with the high performance of its Nehalem (Xeon 5500) processors.

The average megacomputer today is an Intel-based system running some version of the Linux operating system, according to the new data. Microsoft's (NASDAQ:MSFT) Windows grabbed only 1% of the list, and none of the top 10 slots. The top system builders for performance-hungry academic, financial, and government computing needs are Hewlett-Packard (NYSE:HPQ) with a 42.4% share of this list, IBM (NYSE:IBM) at 37.6%, with Silicon Graphics International (NYSE:SGI) and Cray (NASDAQ:CRAY) at 4%.

While the list looks fairly static from most angles -- all of the system builders and operating system providers stayed within shouting distance of the results from last November -- Intel stole a good chunk of prestigious real estate on this list over the last six months. The chip giant moved up from 75.4% to 79.8%, as the Nehalem alone gained a 6.6% foothold in just three months on the market.

IBM only lost a net of five systems using its processor family, or 1%, while Advanced Micro Devices (NYSE:AMD) took a bigger hit, dropping from 12.2% share six months ago to just 8.6% today.

Despite Intel's vast dominance in numbers, IBM is the dominant force behind five supercomputers among the world's 10 fastest, and AMD powers another three (although its processors make an appearance in four of the behemoths). Intel only holds two of those elite spots. The fastest computer alive right now is the "Roadrunner" IBM system that crunches numbers for the U.S. Department of Energy -- with 129,600 processor cores. Sorry, but your homebuilt quad-core box didn't quite make the list. The smallest system here takes 1,152 cores. Maybe next year?

The Top 500 list may seem like a pointless academic exercise, but it's actually a well-respected benchmark that serves as a real marketing tool. It's a way for smaller players like SGI and Cray to get their trade names in front of corporate system buyers, and for the big boys to claim superiority over one another as they negotiate contracts large and small. Besides all that, it's a way to keep track of which high-performance computing platforms are actually being used in the real world.

So the Nehalem architecture is already paying dividends for Intel -- mostly at AMD's expense. We'll have to wait for the next November update to get a read on AMD's Istanbul counterpunch.

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Fool contributor Anders Bylund owns shares of AMD, but he holds no other position in any of the companies discussed here. You can check out Anders' holdings or a concise bio if you like, and The Motley Fool is investors writing for investors.