While Internet Explorer has remained largely unchanged for years, alternative Web browsers like Opera, Apple Computer's Safari and especially Firefox are wowing users with innovative features and the promise of increased protection from hackers.

Firefox rose from the ashes of Netscape, the first popular Web browser, which kick-started the dot-com boom before being vanquished by Microsoft's Internet Explorer. Netscape was then purchased by America Online, which donated the software's code to the non-profit Mozilla Foundation.

After nearly three years of fits and starts, Mozilla has turned out a sleek, fast-running browser. While numbers are hard to come by, more than five million copies of the software have been downloaded in the last two months, and more than a million in the 10 days since its 1.0 "preview" version was released Sept. 15.

Most estimates put Internet Explorer's overall market share at about 95 percent. But a shift can also been seen among the early adopter crowd, which picks up on technology trends months or years before the mainstream.

Nearly a fifth of the visitors to the geeky Web site Engadget (http://www.engadget.com) are using Firefox, compared with 53 percent using Internet Explorer, 11.3 percent using Safari and 2.5 percent using Opera.

"If our audience is the vanguard, I'm wondering if these stars are going to become the norm in another year or two," wrote Jason Calacanis, chairman of The Weblogs Inc. Network, which owns Engadget.

WHY SWITCH?

The most impressive feature of the alternative browsers -- present in Opera, Safari and Firefox, but absent in Internet Explorer -- is tabbed browsing.

Many people run their Internet browsers all day, opening multiple windows if they want to visit several sites at once, or to keep their Hotmail or Yahoo page open all the time.

Tabbed browsing lets you open dozens of sites within a single window, saving space on your computer desktop. If there are a number of sites you visit daily, you can group them into a folder and open them all at once.

The three browsers also block pop-up advertisements, one of the most annoying aspects of Web surfing. Microsoft recently released an upgrade to its Windows operating system that blocks pop-ups.

Among the alternative browsers, only Firefox is open-source, which means that any computer programer can burrow into its code and add customized add-ons to automatically check an e-mail account, control a digital music player, and enable searches of Google, Amazon.com, eBay and the Internet Movie Database.

There are also some more advanced features that will probably appeal only to advanced users, like the ability to view RSS feeds -- short text digests of Web sites -- in the bookmarks menu.

SURFING SECURITY

Internet Explorer has become the target of numerous hacker attacks, reflecting a combination of well-known security flaws, the program's tight integration into the Windows operating system and its overwhelming popularity among computer users.

The alternative Web browsers may prove safer if only because of their relative obscurity, presenting a smaller target for the computer programers who write computer viruses and worms.

They also avoid some features -- such as Active X controls that lets a Web site install a small program on your computer -- that have been blamed for Internet Explorer's security flaws.

But there is a downside to each of the alternative browsers. Since Internet Explorer is still the industry standard, some pages may not appear correctly with Opera, Safari and Firefox.

Opera, created by two Norwegian programers, carries advertising -- similar to text ads seen on Google -- unless the user pays $35 for an ad-free version.

Safari is only available to the small percentage of Web users who use Apple computers. And Firefox has yet to put out a fully polished version, though it released a 1.0 "preview" version this month.

Web sites:

Opera (http://www.opera.com/)

Firefox (http://www.mozilla.org/products/firefox/index.html)

Safari (http://www.apple.com/safari/)