[jQuery] jQuery on a generic registration form

[jQuery] jQuery on a generic registration form

Hi guys,
I recently wrote a simple script for registration forms.  It basically includes AJAX checking if a username/email exists, checking if the passwords match, loading and reloading of captcha.  I feel like there's a lot to improve in this simple script.  It would be great if you can bash my code and point out the parts that can be improved.
Here it is: <a href="http://randell.ph/geeky/2009/04/10/using-jquery-on-a-generic-registration-form/">http://randell.ph/geeky/2009/04/10/using-jquery-on-a-generic-registration-form/</a>
Cheers,
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Randell
<a href="http://randell.ph/geeky/">http://randell.ph/geeky/</a>