Installing NIS 2013

Hi

 

I currently have a 3-PC License for NIS 2012 which expires shortly.  I have one copy of a PC with Windows XP SP3 and the other two on my two Laptops with Windows 7.

 

I have just purchased a new 3-PC License for NIS 2013 as this was considerably less expensive than renewing my current installation.

 

When I install this new version, will I need to remove the existing Version 2012 or can I install over the top of it?