Many webs don`t work the same for Internet Explorer and Mozilla Firefox, so one of them you can see perfectly, while the other is either wrongly boxed or won`t even load some elements. Thus web designers have to continuously verify if their designs work with both browsers.
To solve this problem you can either have both browsers installed or have a tool like NetWorker 2.70, which is a browser that lets you view webs in both browsers, and view the possible design and programming differences that might exist.
This program only works with NT, 2000 and XP. If you want to install it in Windows 95, 98 or ME, you should click here on this other link
este otro enlace.