Two of the last remaining serious Web browser rivals to Microsoft's Internet Explorer each released new versions this week, promising faster and more stable surfing. The Mozilla project, which is creating an open-source version of the Netscape browser, released the beta, or public test of its version 1.5 software on Wednesday. Opera Software, the Norway-based commercial Web software developer, released an updated version of its latest browser on Thursday. Opera's "technological lead is further expanded with today's release," Jon von Tetzchner, the company's CEO, said in a statement. "The feedback from our testers has been unison: Opera 7.20 significantly boosts speed and performance."

For years, the two browsers have been largely responsible for supporting the population of Web surfers who don't want to use Microsoft's Internet Explorer. But that group remains small. According to OneStat.com, more than 95 percent of Web surfers use Microsoft's browser today. By contrast, about 1.6 percent of surfers use Mozilla, and just 0.6 percent use Opera, OneStat estimates. Those figures may be somewhat undercounted, since Opera users often set their software to tell Web sites it is actually Internet Explorer in order to avoid configuration problems. Opera said earlier this month that the most recent generation of its Web browsing software had been downloaded from its site more than 10 million times.