Opera 7 for Windows is both smaller and faster than earlier Opera releases and constitutes a wholesale rebuilding of the browser, the company said.
The heart of the browser is a redesigned rendering engine that provides improved support for established and emerging Web standards like Document Object Model Level 2 (DOM2), extended Cascading Style Sheets Level 2 (CSS2), and HyperText Markup Language (HTML) 4.01.
"We wanted to make things faster and be able to handle more live content. Opera 7 is much faster in rendering and it also starts to render things at a much earlier stage," said chief executive officer Jon von Tetzchner.
Other Opera 7 features include revamped e-mail and news clients, Small Screen Rendering (SSR) technology that will allow Web site developers to see how a particular page would appear on a small-screen device such as a personal digital assistant (PDA) or mobile phone.
Opera's focus on portable devices may be a way to keep the company and its products relevant.
Microsoft's Internet Explorer is used by almost 95% of all Web surfers, according to data from Web researchers OneStat.com. Surfers using the Opera browser account for just 0.9% of the total.
"There is an inherent challenge to companies that are operating system independent to sell a product that comes packaged with an operating system," said Dan Kusnetzky, vice-president of systems software research at IDC.
"They've got to overcome the idea that 'this product came at no additional cost, so why pay for something to replace it?'"
As more and more Web-based services such as online banking standardise on Microsoft's products, the hurdles facing those who use Opera or other browsers can only multiply, said Kusnetzky.
However, with mobile devices the next frontier for purveyors of online content, Opera sees a window of opportunity that is not open in the market for desktop applications.
"On the desktop, I don't think we can topple Microsoft in the near future because they control the distribution," von Tetzchner said. "In the mobile market, however - phones, PDAs, even TV - Microsoft doesn't control distribution."
In that market, the leaner Opera 7 has an advantage over Internet Explorer, according to Tetzchner.
Most mobile devices have comparable computing power to desktop computers of the early 1990s. In addition, the desktop and mobile versions of Opera 7 are identical, making content development for mobile devices using Opera much easier than for Microsoft's mobile Web browser, which is different from the Internet Explorer, Tetzchner said.
Opera has made it known that it is looking to develop deals with mobile device hardware vendors to ship a copy of the Opera browser with their devices.
Opera is also hoping to capitalise on the growing popularity of the Linux operating system. Opera already has a loyal following among users of Linux and Unix and the company is making efforts to increase its support for different Unix and Linux distributions.