When I design Web pages, I test them under Netscape 4.76, Netscape 6.0, Microsoft Internet Explorer and Opera. Basic old-style Web pages do all right. Modern pages -- HTML 4.01 with cascading style sheets -- give me no end of troubles, because different browsers handle them differently.
Netscape 4.76 truly sucks. It implements CSS poorly, barfs on some fairly critical interactive Flash functions, and is full of other bugs. Netscape 6.0 implements CSS better, but it's a slow, bloated resource hog which is also full of bugs. As a diehard condemner of Microsoft's poorly programmed products, I never thought I'd say this, but Internet Exploiter is actually a better browser than Nutscrape.
Of course, Opera is probably the best Windows browser available, even if the Google Toolbar isn't yet available for Opera. It does have a Google search box built in, but that pales in comparison to the nifty features of the Toolbar.
Opera, like Eudora, is a commercial product which can be used for free if you permit it to display advertisements. I've been using the Web for so long that I no longer notice banner ads; they don't even impinge upon my consciousness.