Microsoft said one key feature in IE9 was tools to stop people being tracked as they move from site to site. This information is often gathered by commercial firms to tailor ads to the specific habits of web users.
In addition, said Microsoft, separate tools in IE9 keep an eye on downloads so they can spot when viruses and trojans try to sneak onto a computer.
IE9 also has hardware acceleration built in so it can call on the power of a PC's graphics card to display sites in more detail.
chrome is the best imo, however ff and chrome go head to head in terms of performance. Any of the two is a good choice, if your still using ie quit the internet.