Mozilla Firefox Upgrade

I have Mozilla Firefox setup as my home page on my laptop at home to access the Internet. About 3 to 4 days ago, after I click my little icon on my desktop, this “URGENT” exclamation icon displayed stating that my version is no longer protected against online attacks. Of course, it stated for me to get the upgrade because it’s free and faster. My questions and concerns that I have with that is…. Why wouldn’t you continue to support an older version from online attacks? Why do you want me to upgrade? Now because I don’t like change when it comes to certain things am I opening (exposing) myself to attacks online? I have included the link http://www.google.com/firefox?client=firefox-a&rls=org.mozilla:en-US:official for you to view if you all like. The new Firefox 4 is in Beta testing and ready for you to download and try out for those advertisers. They are implementing a “Do Not Track” is a program for online behavioral mechanism. According to the website it’s just advance option that you checked when you don’t want to be track for online behavioral. The thought process is to use a header filter that is simple and to avoid the user setting and loading to a network. Although this is a nice feature to have when you are browsing the internet, however, this will not stop hackers or anyone from hacking into your system. If at all it will be a challenge to see if they can get through. I wonder how will this information been seen in the IRC now.