Should a Minister Wear a Robe and a Collar? (Audio only)

Should ministers wear preaching robes and clerical collars? Well, this is certainly in the realm of adiaphora (i.e., things "indifferent" or "non-essential"). The Bible doesn't require someone to wear a robe or a collar, but why might some pastors choose to wear them? What is the reasoning behind wearing them? 

For more information, see: 

A Pulpit Is Not A Platform (article) by R. Scott Clark 

A Short History of the Wearing of Clerical Collars in the Presbyterian Tradition (article) by Tim LeCroy