Which method performs better: .Any() vs .Count() > 0?

In the System.Linq namespace, we can now extend our IEnumerable's to have the Any() and Count() extension methods. I was told recently that if I want to check that a collection contains one or more items inside it, I should use the .Any() extension method instead of .Count() > 0 because the .Count() extension method has to iterate through all the items. Secondly, some collections have a property (