I assume that you actually want where the name attribute is "FirstAttributeName" since there is nothing named "FirstAttribute" in your sample.
This should give you what you want.
SELECT per.value('(Data/item[@name="FirstAttributeName"])[1]', 'varchar(50)') AS FirstAttribute
You will still need to use the [1] since the value() function requires a singleton.
Drew
J. Drew Allen
Business Intelligence Analyst
Philadelphia, PA