How to make AOL my default mail

Hi Experts,
I am using an Acer laptop that is operating on Windows Vista. I have installed AOL as my email. My mistake is that on the start up of the program, I forgot to choose AOL as my default email.
Now, I am having a problem locating the AOL email in the programs drop down. I know there should be some way for me to make it my default even though I was not able to choose that option the first time. I searched in my Internet Explorer 7, but too many search results to choose from.
Please help me make AOL my default email. Thanks.
