Create HTML / Txt Template Valid on all email clients

We have created a HTML email template using mailchimp, but the problem is the email does not work correctly in different email clients. It is broken in Outlook 2007 and others. We need someone to take our existing design and re-create it from scratch into a completely valid html email design. We will also need it converted to a txt based version too. The successful person will need to test the template they create in all major email clients and make sure it is compatible with mailchimp. The successful person can also redesign the template to make it more compatible.