Single label DNS Vs Dual label DNS

Hi folks,
I have a server2003 server that I am going to migrate to server2008 (hurrah!), however, it has only got a single label for dns name. I have read somewhere this may complicate the migration.
My questions are;

As I am not going to be using Exchange, do I need to change this single lable for a dual label?
Is it going to be easier to change the label before I migrate to server2008?
Can the label be changed as I migrate to server2008?

Thank you for your consideration.