The status of 'Netscape' as a competitor to Internet Explorer
Web design is the practice of creating web pages and web sites to go on the internet, which should be accessible by the largest audience reasonably possible. To make your creation behave for the most people possible, you will need to maintain support for the most current browsers possible. Luckily someone came up with web standards to which most current browsers mostly conform. When testing your creation for cross-browser compatibility, it is no longer sufficient to test it in "IE and Netscape".
Netscape the company was acquired and subsequently shut down by AOL. Netscape the browser still exists, but simply as a bloated re-branded version of Mozilla. Since Netscape 6.0, the core has been based off of Mozilla and hence "Netscape" as a browser technology simply does not exist.
Instead, if you are to ensure the compatibility, accessibility, and longevity of your creation, you might want to make sure all of your documents conform to a web markup standard, whether it be HTML 4.01, XHTML 1.0, or XHTML 1.1. After your document validates, you can then test it in Internet Explorer, Mozilla Firefox, Opera, Safari, Konqueror, and any other browser you can get your hands on. The point is that you should be developing for a common standard that browsers can target, rather than developing for any specific list of browsers.
When trying to develop for the largest possible audience and maintain a nearly identical result in all browsers, I (h3h) personally recommend you develop your page using Mozilla Firefox to check your progress as you go. After you have finished the bulk of the development, view it in Internet Explorer and make any appropriate fixes, while maintaining your desired creation in Firefox, Opera, and Safari. I have personally found that development is much faster and simpler when using this method.