Just this morning, I was asked "My site looks fine to me.... doesn't everyone use Internet Explorer?"
Um, no. They don't. Lots of people have Macs and they will probably use a browser called Safari, which is also available for the PC now. Other people (like me) use a browser called Firefox, because it has lots of add ons and is a bit more flexible.
It's true to say that the majority of people use Internet Explorer (IE) but, recent figures have the market share for IE at somewhere between 57% [W3Schools] and 77% [Net Applications]. That means that in any given thousand visits to your site, between 330 and 430 people may not see your site at it's best. Eeek!
To check out how your site looks to people who aren't using IE, download the browsers below: Firefox Safari Opera
And if you haven't already upgraded to Internet Explorer 8, you probably should.... Internet Explorer
So, make sure your website works across these browsers. If it does, it will have the pleasing side effect of being more accessible to the two million people in the UK who have a sight problem [RNIB] and the one in twelve people (or 9% of the UK population) who have some form of colour blindness [IEE].
If you're concerned about your site, and don't have the time to chase your web designers to fix it, my website accessibility review will give you an analysis of how your site performs against industry best practice. I'll provide you with a written report of where improvements need to be made, with the technical documentation to give to your web designers so they can make it happen.