Microsoft is by far still the top dog in Web browsers, but competing efforts to offer a window to the Web continue, as evidenced Wednesday when Norwegian browser firm Opera Software, and open source browser group The Mozilla Organization both released betas versions of their respective software.

Opera released Opera 7.20 for Windows Beta, a release that continues Opera's push to internationalize with support for bi-directional languages like Arabic and Hebrew.

"Opera 7 has been greeted with cheers from users and press all over the world," said Jon S. von Tetzchner, CEO of Opera Software. "By continuously listening closely to our users throughout Opera's development cycle over the years, we have succeeded in creating the very best browser their is. This technological lead is further expanded with today's release. The feedback from our testers has been unison: Opera 7.20 significantly boosts speed and performance."

Meanwhile, Mozilla pushed out Mozilla 1.5 Beta, which includes a host of new features and is the first Mozilla milestone to include a spellchecker for MailNews and Composer. Mozilla said the release, which is available for Windows, Mac and Linux users, improves performance, stability, standards support and Web compatibility of the browser.

Opera and Mozilla (which powers Netscape, although AOL Time Warner recently separ ated itself from the development group and now operates under the non-profit Mozilla Foundation) have become Internet Explorer's closest rivals, though "close" is relative term.

According to W3Schools, an organization which offers free tutorials on World Wide Web Consortium standards and maintains monthly browser statistics, IE 6 and IE 5 together currently hold 86.9 percent of the market. Opera 7 has 1.7 percent share. Mozilla has 5.9 percent share, or 7.9 percent if Netscape 7 is included.

But as Microsoft continues to tie its browser more closely with its operating system, Opera said it sees an opportunity to increase share.

In a chat hosted by Microsoft TechNet on May 7, Brian Countryman, program manager for Internet Explorer, said, "As part of the OS, IE will continue to evolve, but there will be no future standalone installations. IE6 SP1 is the final standalone installation"

Countryman explained that legacy operating systems had reached their zenith with Internet Explorer 6, Service Pack 1, and that further improvements to the browser would require enhancements to the underlying operating system.

"Microsoft will not develop the stand-alone version of Internet Explorer further, instead going for full integration in the upcoming 'Longhorn' operating system to be released in a few years time," Opera said. "Internet Explorer users thus need to buy a new operating system to get a new browser. This leaves Opera as the only major commercial player continuing to push browser development, offering a vast number of new users a continually up-to-date and enhanced Internet experience."

Like Mozilla, Opera offers its browser on numerous platforms, including Windows, Mac, Linux, OS/2, Solaris, FreeBSD, QNX and Symbian. The browser-maker has been increasingly penetrating devices beyond PCs, including smartphones, PDAs, iTV and vertical markets (automotive telematics, manufacturing and transportation).

As part of the Opera 7.20 for Windows Beta, Opera has also initiated a "Happy Hour" campaign. The company said that during two random hours every day for the next 10 days, Opera is available with a 25 percent discount for $29.95.