Was a little disappointed with their newish update with regard to header and footer integration. They now only permit a small logo on the order and purchase pages.
An extract from the 2CO site :
Effective Friday, April 1, 2005 the headers and footers feature will be disabled on both V1 and V2.
In order to satisfy requirements and guidelines established by the credit card associations, 2CO can not support vendor based Headers and Footers on the Billing Information pages at this time.
Because we know that branding and integration are important to you we have enabled a Logo Feature which will Display your Logo on the Order Details page. Logos, unlike headers and footers, will also be included with all shopping center based orders. This will also allow vendors to benefit from 2CO's marketing efforts with third party outlets like Froogle and Yahoo Store.