Since a lot of programmers were overwhelmed with the and attributes, with .NET 3.5 SP1, Microsoft made the data contract serializer handle all classes - even without any of those attributes - much like the old XML serializer.
So as of .NET 3.5 SP1, you don't add data contract or data member attributes anymore - if you don't then the data contract serializer will serialize all public properties on your class, just like the XML serializer would.
by not adding those attributes, you lose a lot of useful capabilities:
1) without , you cannot define an XML namespace for your data to live in.
2) without , you cannot serialize non-public properties or fields.
3) without , you cannot define an order of serialization () and the DCS will serialize all properties alphabetically.
4) without , you cannot define a different name for your property ().
5) without , you cannot define things like or other useful attributes.
6) without , you cannot leave out certain public properties - all public properties will be serialized by the DCS.
So for a "quick'n'dirty" solution, leaving away the and attributes will work - but it's still a good idea to have them on your data classes - just to be more explicit about what you're doing, and to give yourself access to all those additional features that you don't get without them.