Where does the Add Account information auto-populate from In System Preferences, under Mail, Contacts &amp; Calendars if you add an account (Microsoft Exchange or GMail) a few of the fields are auto populated (ie Name and email address).

Where is this information pulled from?

I suspect it is from the information entered when you register the Mac on first boot. Can someone please confirm this?

Also, is there an easy way to modify this information so it doesn't autofill with the incorrect name/email?

Thanks.
There should be a contact in Contacts.app which has a little head and shoulders silhouette next to it in the list and a grey bar with "me" across the picture. 

I think you are right that this is created when you first started using the computer.