BleepingComputer.com: Internet Explorer and Updates will not run but I am connected to the Internet

I have an HP Pavilion a1483w running Windows XP Media Center Edition 2005 get an IP address and show that it is connected to the Internet but will not let me browse the internet or run any updates. I have installed a newer version of IE because I thought that maybe the version I had was so out of date but I still can not browse or update windows or my anti-virus. I have also double and triple checked all my connection settings and everything seems to be in order. Any help will be greatly appreciated. Thanks