Tracking Adwords Signups Help

I am looking for the best way to track multiple ad words goals on my Ad Words campaign.

Goal #1 is easy enough to setup – I can post their code on wp-signup.php and it will tell me how many visitors are getting to the signup page. What part of the code would I insert “Goal #2’s code” if i want to be able to tell when a user account is generated – without hopefully double tracking the initial goal ?

A plugin for this would be nice and I assume fairly simple but I guess demand is low due to such few people using Ad Words for their WPMU / Buddy Press sites which I understand. Just surprised not to see more chat about it in these forums.