NIS 2011 Performance Pack

I wonder if someone can help me!

 

I currently have NIS 2011 (3 PC's upgraded from NIS 2010) installed & usually renew my subscription by purchasing a new disk & simply entering the product code.

I would like to purchase NIS 2011 + Add on Pack (3 pc's as it is on offer).

 

Would entering the product code for NIS 2011 + performance pack, activate my subscription as in the past (NIS 2011)? or would I have to uninstall NIS 2011 & perform a "clean" install of NIS 2011 + performance Pack?

 

PC 1 Windows 7 Home Premium 32 Bit

PC 2 Windows XP Pro 32 Bit

PC 3 Windows XP Pro 32 Bit  (Laptop)

 

Thank you for you your assistance