SAN FRANCISCO -- Apple's ( AAPL) Mac operating system continues to win over a growing number of computer users and chip away at the dominant lead of Microsoft ( MSFT) Windows. Data tracker Net Applications said Monday that Apple's global share of the personal computer market rose to 6.6% in September, up from 4.7% in the same month last year, and higher than 6.15% in August. Net Applications attributes the gains to Apple's use of faster Intel ( INTC) processors in its Mac. Intel-based Macs began shipping in January 2006. The increase in market share showcases Apple's growing appeal to consumers outside its traditional niche audience of Mac enthusiasts, graphic artists and educational professionals. In addition to the use of Intel processors, analysts and investors say the company's wildly popular iPod has brought more attention to its computers -- the so-called halo effect -- helping it capture a greater share of the mainstream market. Microsoft's Windows operating system still commands the vast majority of the computer market. But its total market share fell to 91% in September from 94% a year earlier. Vista, the latest version of Windows, held about 7.4% of the market in September. Investors expect Apple to notch further market share gains after it releases its Leopard operating system in October. The company demonstrated a preliminary version of Leopard in June, highlighting features to help users organize email and desktop applications and run Microsoft applications.
Earlier in the year, Apple delayed Leopard's release because it had needed more software engineers to help keep the iPhone's debut on track. In the meantime, however, it has updated its line of Macs, giving them more features at the same or lower prices than previous models. Macs still cost more than most Windows-based PCs, with the least expensive model retailing for $1,199. Nonetheless, preliminary estimates suggest that Mac sales will
widely exceed analysts' forecasts . The market share data also show that more people are using Apple software to access the Internet. Apple's Safari Internet browser accounted for more than 5% of Internet traffic in September, compared to 3.53% a year earlier. Investors are banking on strong Mac sales to beef up Apple's already impressive financial results. At prices that are much higher than iPods and iPhones, Mac sales are a major plank of Apple's revenue. Its margins are also higher than iPods, which have seen sales growth fall precipitously as lower-end models sell in much greater numbers than premium versions. Gauging the Mac's profitability against that of the iPhone has proved a challenge for investors and analysts because of uncertainty around the cost of components, the fees Apple charges AT&T ( T) and its piecemeal accounting for iPhone sales. Apple shares were recently up $2.34, over 1.5%, to $155.81, just shy of its all-time intraday trading high.