The Firefox browser regained some of its heat in October, as its market share was lifted by the announcement that the open-source browser had achieved its 100 millionth download, a Web monitoring vendor said Friday.

The browser, developed and marketed by the Mozilla Corp., increased its average usage share to 8.59 percent from 7.55 percent in September, NetApplications said. Microsoft Corp.'s Internet Explorer, meanwhile, dipped slightly to 86.52 percent from 86.87 percent.

Firefox's rise in the market place had stalled over the last three months. The browser, however, appeared to have benefited from Mozilla's marketing announcement of 100 million downloads. In the final week in October, Firefox's market share peaked at 8.65 percent.

The browser, however, has yet to reach its peak for the year, which was an average 8.71 percent in June, NetApplications said. The browser started the year at 2.69 percent in January.

By year-end, Mozilla may get another boost for its browser with the release of Firefox 1.5, which promises improvements to the automated update system, Web site rendering and performance, as well as several security and bug fixes.

In other browser news, Apple Computer Inc.'s Safari continued to show modest, but steady growth. Over the last 12 months, Safari has made gains each month, reaching 2.56 percent in October. The Mac OS, which ships with Safari, was up to 3.87 percent usage share in the month, NetApplications said.

"When the (Apple) iPod's success is combined with Macintosh market share gains, it appears that Apple is definitely on the right growth path," Vince Vizzaccaro, executive vice president of marketing for NetApplications, said in a statement.

Rounding out the top five browsers were Netscape, which saw its share drop to 1.26 percent from 2.16 percent in September; and Opera, which was nearly unchanged at 0.54 percent from 0.51 percent.

NetApplications based its figures on data collected from more than 40,000 Web sites monitored globally by the Aliso Viejo, Calif., company.

The numbers were significantly lower than those of Dutch Web metrics firm OneStat, which reported this week that Firefox had broken the 10 percent mark to 11.5 percent usage.