Dell Inspiron 1525 - Connected to wifi but still no internet connection

I recently just received a Dell Inspiron 1525 and it connects to the wifi just fine but anytime I open a web browser it just says that I have no connection. When I diagnose for connection problems it says that everything is working fine. Now I don't have the McAfee security thing I uninstalled that already and I spent all night doing update after update and still nothing. I am starting school here soon and the laptop I have doesn't support the programs I need to use and this laptop should but I need internet to be able to send things to emails and whatnot.