IE is very slow, incompataible and renowned for poor security whilst browsing. It can allow attackers direct access to your computer, bypassing internet security : Google, Adobe and even the Australian government were all hacked via IE. Using IE is often said to be the quickest way to become infected. It's not required to connect to the internet as your LAN, WiFi or modem connection does that. It's a very rare day when IE, Firefox or Google Chrome is not infected.
Firefox is very basic, incompatible and unsafe. Each version has 1000s of bugs, many beta releases and relies on 3rd party 'plug-ins' to provide functionality.
Google Chrome is fast but basic and unsafe - worse than IE.
In my opinion Maxthon Cloud Browser is the way forward for all the reasons I mentioned above.
Opera is fast and safe and its Opera Turbo mode can speed up a slow internet service such as TalkTalk, BT, Sky and Orange.