It's generally accepted among tech geeks that Internet Explorer is an awful, clunky web browser to use. Most people who use the Internet for a living probably end up choosing Firefox, or Chrome, or Opera, or Safari, or what-have-you. The vast majority of users, however, are still totally comfortable with IE. That's why it holds a commanding percentage of the browser market.
After September though, it has less of a lead than it once did. According to studies by web metrics firm Net Applications (via ZDNet) Internet Explorer's overall market share dropped by 1.26% in the month of September. It is now down to 65.7%, which is still a substantial lead, but less of one than Microsoft has had in years.
Firefox, by comparison, is up .77% this month, to 23.75%, which makes it the only serious competitor that IE really has. Chrome doesn't come in close to either of them, with 4.24% of the market (it rose .33% last month). It isn't happening quickly, but people do seem to be turning away from IE in increasing numbers. Maybe because we have more net-savvy folks these days than ever.
On an interesting note, Windows Vista saw its first drop of share since January 2008 this month. It's down .18%, to 18.6% of the total OS market. This is almost certainly due to the imminent release of Windows 7. No one wants to buy a Windows Vista machine when they know that a vastly superior operating system is only a few weeks away.
Win 7, by the way, also saw a jump this week. It now holds 1.52% of the market share. This is impressive, primarily because the product is not out for retail yet. I think we have piracy to thank for Win 7's early lead. You wacky torrenters!