Here's what the difference between the companies boils down to: Microsoft is focusing on today's Web, and the rivals are focusing on tomorrow's.
This sums up many of the comments that I have made about browsers over the months [see Does the browser really matter?]. The browser is not a passive browser any more. It is a Web application portal/container. With MSIE8, Microsoft has not made the leap into the future web.
It has produced more of the same, and will likely continue to see its percentage of the market drop, at least until Windows 7 rolls with MSIE8 installed as the base browser.
My final comment is that Windows 7 may not be enough to save Microsoft entirely due to the economic downturn and its effect on the upgrade process within households and corporations.