If you haven't upgraded your browser in a while then there are a number of very good reasons you should. A modern web browser will be much more secure than an out-dated one, even one that is fully patched. It can protect you from the many threats that are out there, will be faster, and more capable at handling the latest the technologies such as HTML5.
IE9 is just such a browser.
If you're running Windows XP and you've never upgraded then you'll be stuck with Internet Explorer 6. This is not good. For a long time IE6 was the most popular browser in the world but having first appeared in 2001 it's now over a decade old. As such, it soon became a victim of its own success and became the target of nefarious attacks from hackers, and found itself much maligned for its vulnerability. Unfortunately, Windows XP users won't be able to upgrade to Microsoft's latest browser Internet Explorer 9 as IE9 will only run on more modern operating systems such as Windows Vista and Windows 7. This is down to the fact that IE9 requires Direct2D for its hardware acceleration, which is not available for XP. (At the very least then, you should be running IE8).
If you want to upgrade to IE9 but don't want to buy a completely new computer you'll need to upgrade the operating system to Windows 7. You should check your hardware specifications first but the good news is that if your machine can run Windows 7 it can handle IE9 comfortably.
For the record, the basic requirements for IE9 are a computer with a 1GHz CPU and both 32-bit (x86) or 64-bit (x64) support. If you're still on Windows Vista, you'll need to be running Service Pack 2 (SP2). You'll also need at least 70MB of free space and a display with a minimum resolution of 800 x 600. Needless to say, an Internet connection will be pretty useful too. If you don't have any of these, then computing wise, you have bigger problems than your browser!
If you're on IE7 and IE8 though the easiest method of upgrading is to go to Windows Update. To do this in Vista and Windows 7 press the Start button and just type 'Update' in the search box. From here your Windows Update will search and find all updates for your computer, including IE9.
While in almost all cases the IE9 installation process will retain your favourites and shortcuts, if you're concerned, then you can back them up manually. To do this in IE8, go to File>Import>Export Favourites and then save the HTM file to your desktop. From here you'll be able to reverse the process and import them should the need arise.
When you upgrade from IE8 you'll find that your favourites have been moved. If you back these up manually you can easily import them again.
Once you've upgraded, you'll find that things look different. If you discover that your menu bar, with File, Edit, View, etc. is missing then fear not; Microsoft has simply removed toolbars by default in order to give more space to webpages. If you need to access to them simply move up to the top of the browser and right click anywhere except the address and menu bar. From the context menu you can easily restore the Menu, Favourites and Status bar.
Restore missing toolbars by right-clicking on an empty area at the top of the browser.
For many IE users their Favourites list is the way they get to the sites they use most frequently. In IE8 this is located on the Favourites bar. In IE9, you can now access this directly by clicking on the Star at the top right - the middle of three buttons. Click this and your Favourites will appear. Next to this you'll find the tabs for your History and your RSS feeds, all neatly combined in one place.
Another possibility is that after you load up a page in IE9 it might not look quite right, especially if it's an old webpage, with problems such as out-of-place images, menus or text. As IE6 was around for so long, many sites were designed with it in mind. However, this meant that often websites were built to work with IE6, rather than web standards. IE9 fully support the current W3C standards, so there's a chance that the HTML and CSS on older sites may not be rendered as originally intended. For help with this IE9 has a compatibility button that site will fix many problems. Simply click the icon that looks like a broken page and sits to the right of the address bar.
Sites that are designed for IE6 may not look right - this can be fixed with the compatibility button.
If you're a website creator and you want to know how things may look in IE9 then Microsoft has put together a tool called the IE9 Combat Inspector. This will examine your code and tell you what parts of your site might not comply with web standards, and will therefore be a problem in IE9.
What's more, if your business runs web apps using IE6, the sensible thing to do would be to install IE9 on one machine, and test how they run in IE9, especially if they're business critical.
Microsoft can help here too, and has tools such as Expression Web 3 SuperPreview, which will let you compare how sites will look in IE6 and IE9 at the same time. Another method for testing would be to run IE9 on the same machine using desktop virtualisation.
Alternatively, if you've got an IE6 app and don't want to rearchitect it, then Windows 7 XP mode will do the trick. This runs Windows XP, within Windows 7, so you can run IE6 virtually within that. If you've got a mission critical IE6 app that just won't play nicely with IE9, it's a great solution.
Finally, if you've been using IE8, you'll already be familiar with the concept of 'Add-ons' and might have several installed. Add-ons are plug-ins that run in IE and provide extra functionality, from ubiquitous ones such as Adobe Flash to shopping tools. Be aware that unless the Add-on provider has updated the program there is chance it won't run in IE9. However, as Microsoft's latest browser has been out for several months now, there's a good chance it will be ready to roll in IE9 and you can enjoy the web as it's supposed to be.