Set Up an AOL Instant Messenger Account on iChat

Have you recently switched from a PC to a Mac and want to transfer your AIM screen name to iChat? All you'll need is your computer and a little time.

Steps

Open iChat. The icon should be in your dock if you haven't removed it, and it looks like a speech bubble with a video camera inside.
Open the Preferences window. This is found under "iChat" on the Menu Bar. Or you can use the keystroke "Apple-comma". (⌘,)
Click on "Accounts".
Press the plus (+) button at the bottom of the window to add an account.
Select "AIM Account" on the dropdown menu.
Type in your information.
Start chatting!

This also works for .mac accounts, MobileMe accounts, Google Talk accounts, and Jabber accounts.
You can make a screen name for free at the AIM website.
If you don't feel like configuring this and don't mind downloading things, you can download the Mac version of AIM at the site above. However, it still has some glitches and you will need to be patient.

It isn't particularly smart to choose the "Automatically Login" option because while it's convenient, someone could just walk up to your computer and click on iChat, accessing your buddy list and essentially stealing your identity. Do not use this feature on a shared computer.