According to Net Applications' February data, both Firefox and Safari accounted for slightly larger slices of the browser pie than the month before. IE, on the other hand, slipped by nearly the same amount.

Firefox, which sports versions for Windows, Mac OS X and Linux, climbed to 14.2 percent from January's 13.7 percent. Safari, which is bundled with Mac OS X, rose as well, to 4.9 percent from 4.7 percent. Internet Explorer's share dropped to 79.1 percent from last month's 79.8 percent.

"After a minor hiccup in January, Firefox seems to be back on the offensive in February," Vincent Vizzaccaro, Net Applications' executive vice president of marketing and strategic relationships, said in an e-mailed newsletter. "January showed a brief halt to Firefox's assault on Microsoft Internet Explorer's market share. Could that have come from new Vista machines? Possibly, but it appears that browser users have gone back to switching to Firefox, Safari and Opera."

Opera, a browser from a Norwegian company by the same name, increased its market share slightly, from 0.73 percent to 0.79 percent.

The newest versions of both Firefox and IE, meanwhile, also boosted their share during February. Firefox 2.0, released last November, climbed to 7.8 percent, a 1.5 percent one-month gain. IE7, which runs on both Windows XP and Vista, increased to 29.1 percent.