i\'ve got a sign up wizard for new user registration. When I try to goto the 2nd page, I get validation errors because my User
object hasn\'t been fully populated,
You can use the Bind Attribute for this: http://ittecture.wordpress.com/2009/05/01/tip-of-the-day-199-asp-net-mvc-defining-model-binding-explicitly/
A better option would be to use ViewModels.
http://weblogs.asp.net/shijuvarghese/archive/2010/02/01/view-model-pattern-and-automapper-in-asp-net-mvc-applications.aspx