Cannot log on to my Outlook 2007 due to MS

Cannot log on to regular account using Outlook 2007 due to Microsoft Exchange. Everytime I open MS Outlook 2007, MS Exchange wants to log on. I get the error saying that MS Exchange is unavailable and that Outlook can’t log on, saying that I need to verify if I am connected to the network.
I am running on Vista and my default mail is Gmail. How do I prevent this behavior and delete MS Exchange?
I tried to delete Exchange in my accounts but the system prevents me from doing so, saying that the configuration info is being copied.
Please help me.
