Perhaps you do not know it, but Internet Explorer is not the only web browser! There are dozens of others. The general problem is that web browsers do not necessarily understand the used language in same way to design web sites. For xHTML, it does pose almost no problem (in fact, Internet Explorer does not understand some things, but this is of little importance), while the CSS for its shortcomings are much more problematic. Recognizing that Internet Explorer was losing more and more market shares, Microsoft has decided to offer him a youth leaving with the version 7 of its flagship browser, with the menu, as far as we are concerned, a better compliance for CSS specifications. It is still far from but progress is still significant compared to version 6.
Another browser very fashionable at the moment who can eat market shares to Internet Explorer, it is Firefox. This browser has advantages over its main rival with better support for CSS and a huge amount of extensions enabling it to be highly customizable. It is also slightly faster to view web pages than Internet Explorer, and is more secure than the latter. Its main shortages are its catastrophic resource management (consumed resources, tabs resource management, etc.) and a slow loading and using.
Last browser that I will present, Opera. This web browser offers a compliance for CSS and xHTML standards unparalleled. In addition, it is significantly faster than Firefox and Internet Explorer to view web pages. It also includes many functions, without having to install extensions. So much the better, because the available extensions are few compared to Firefox. It is a very lightweight browser, which uses little memory and CPU. It may therefore be installed on an old machine without significant slowdowns. This browser is also the most secure of the three right now. In short, I advise you this web browser!
When you create your website, try to test it on all these three browsers. You will be assured of having a maximum compatibility with almost any other browser visiting your web site.