mapping xml path in a web project

Hello
I am using a xml file to get some values. 
I am reading xml like this
Dataset ds = new Dataset();
ds.readXml(Server.MapPath("XMLFILE.xml");
I want to know that is this a better method to read xml file or storing xml path in web.config file and then using it is a better choice.
I think both are same :) but it would be great to know if there is any advantage
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