whether u like it or not, 80-85% of web visitors use IE . But from a developer point of view, most people prefer firefox becoz it supports various addons (which are of immense help)
I think IE market share is only that high in the highest estimates.
It also varies depending on the type of websites, I did a search and found some recent numbers for IE market share, they vary quite a bit, here are four: 57% 81% 67% 40%
A lot of the higher numbers come from older stats, lower numbers seem to come from stats generated by more high tech sites as the 'geeks' tend to use Mozilla Firefox browsers.
I couldn't agree with you more about the FF plug-ins that help with development, I use Firebug, Web Dev Tool Bar, and some others I can't remember the name of, they are pretty much mandatory for me, otherwise I would be staring at a locked up web page wondering what's wrong with it.
Those plug-ins help with Javascript, httprequests, css, forms, everything, just amazing!
And although Firefox currently is easier to develop for CSS, IE is much better with Javascript and AJAX (since AJAX is their technology)
IE doesn't use Javascript, it uses
JScript.
If you do any Javascript programing you will quickly run into the differences between JScript and Javascript because your Javascript will not work in an IE browser.
AJAX (Asynchronous JavaScript and XML) is just method of loading new data into a web page that is already in the client browser using Javascript to perform http requests and to receive and parse the XML document passed back in the http response.
IE was the first to have this capability via XMLHttpRequest, but FF has had the capability for 5+years now, you would have to show me an example of IE being better at implementing AJAX than FF for me to believe it.
The reason FF is much easier to develop for is that it predictably renders your web page based on W3C standards, if IE8 will be standards compliant that would be great, I would still prefer FF, but maybe I wouldn't hate IE so much then.
Standards aside, most web pages I look at look better in FF but some pages look
much better in IE7, nothing looks better in IE less than 7.