Hey SamColes - The table itself was just an example to show setting up a table properly (not necessarily a view on how wide it should be). The whole width question is a more of a design call than anything else. I am trying to keep it as design-free as possible.
There are however many interesting uses for wider than normal emails. In any case, I updated the example table to be 600px wide.
600px may be fine for Hotmail, but I think the bigger question is how to deal with people reading this HTML mail on mobile clients with smaller screens. People are reading alot of email on mobile devices and its increasing. A table 600 px wide is still to wide for most devices.
hey ryanwatkins - one great way is to @media queries to set specific design for mobile and tablets. it is something i am working on for next release.