You might have heard that Microsoft lost a lawsuit to include Internet Explorer with their Operating System, now they'll ask you which one you want to install.
This is the Web Browser you are probably using right now.
Microsoft recommends this browser and says it's "more stable" and "more secure", because it's been build for Windows.
Now, as you can read in this article Windows is not so stable and secure at all.
I do not only recommend, but by reading this article I grant you the wisdom NOT to choose Internet Explorer.
-There is no reason at all to use Internet Explorer.
-Crashes a lot.
Apple's version of Internet Explorer, not quite as bad as IE but not as good as other browsers.
-Not very many people are using it.
Quite a good browser, but it's pretty slow.
-Supports pretty much every website.
-Built-in spell checker.
-Slow, but not as slow as IE
Used to be my choice of a browser for Windows, but Google is probably collecting information from you (it has been confirmed they collected information from wireless networks while doing streetview).
-good website support.
-Google is watching you.
-Mac version is very poor.
The most secure and fastest browser on Windows, poorly it doesn't support every website (which is usually the webmaster's fault).
-Very, very fast.
-Built-in spell checker (at least on the Mac version).
-Not supported by a small number of websites.
Not very popular, but about twice as fast as any other browser.
-Great support of websites.
-makes great use of the Mac OS only features.
-Built-in spell checker.
So, which browser is the greatest?
Well, it differs per Operating System and your needs.
Want to customize and have a browser that runs at decent speeds? try Firefox.
Have a Mac and want the best speed? have a look at Camino.
Every single tested browser is free, and I'm not sure if there are paid browsers, but they're probably not any better.
I recommend testing out all the ones in the top 3 of your Operating System.
No, downloading these browsers will not give you viruses (and neither will most free applications you can download online).
I'm pretty sure all of the browsers support your language, spell check might not be available in your language.
Windows top 3:
Mac OS-X top 3:
I have not used Linux long enough to try out enough browsers, I just know Firefox and Opera are both great browsers for Linux.
Oh, and the browser I'm currently using? Firefox OS-X, as I can't live without it's plugins.