You could be, if they visit your website and it only works in Internet Explorer (IE).

I wrote 18 months ago about how IE was losing market share, at the time it was 70% of the browser market, now it's down to less than 60%.

This means if your website doesn't work, or doesn't work well, in any browser apart from IE customers and clients will see you as un-professional and will most likely go back to google and pick the next website down the list.

Can you afford to lose them?

A website can easily be constructed in a way which means it works, in every browser, on every operating system, all the time.

Every site from TempleDene does, It's built into the system so you don't even have to worry about it.

It is no longer appropriate to look at your site in IE and ignore browsers such as Firefox, Opera, Google Chrome and the rest. Dismissing them as minority browsers means over 40% of people visiting your site are not seeing what you want them to see, or possibly not being able to see your website at all.