Not everyone signs up for Google AdWords at the same time as Google Analytics. In fact, I ran into a similar problem as I tried to link an existing Analytics account to a newer AdWords account. When I tried to set up Analytics through Google AdWords, it created a brand new Analytics account instead. It didn't seem possible to get my other Analytics account in there.
In a Google Groups thread, this question about linking Google Analytics accounts comes up. (Thank you for reading my mind ... almost!) Is it possible to link two Google Analytics accounts to one Google AdWords account?
According to AdWordsPro of Google, this is not possible: "Each AdWords account may be linked to one Analytics account only."
However, according to AdWordsPro, you can unlink the Analytics account, and you can possibly link to the other Analytics instead by following the steps below:
In order to unlink AdWords and Analytics accounts, you will need to contact the Google Analytics Team. They'll be happy to take care of this for you.
Please contact the Analytics Team through the link below and include the following information:
* Your Google Analytics account ID (click Edit Analytics Account from your Analytics Settings page to display this value) * Your Google AdWords customer ID (shown at the top right of any AdWords account page)
Cool. Good to know.
Discussion continues at Google Groups.