Problems with My Vista Laptop

Hi everyone.

I had my HP Vista laptop for 7 years now and very attached to it. It was recently hit with a Virus and now I plan to install Win8 as a clean install and get rith of Vista .

I am not sure what to do. As my Laptop is infected do I first install Norton Internet security , remove the Virus , do a back up of my data files on a back up drive, install Win 8 and then reinstall Norton.

Or do I back up my infected files on a backup drive (which already has data on it) , Install Win 8, then Install Norton then clean up all the Virus on the machine, then restore the data files and directories and then do a second scan of the new installation?

 

Which is the best option for me. Option 1 means I need to install Norton twice once on Vista to clean it up and the second time  Win 8 , but can I install one copy of Norton on two different installations?

Option 2 means I need to install Norton only Once, but I will be installing a Win 8 on an infected machine !!!

 

TIA for any advice