When you have the new system and before going online:

  • Put Avast on it
  • Put a firewall on it

Then go online and visit Windows Update and make sure you have all security patches/fixes installed for Windows as well as for MS-Office (if that is installed)

Install the applications you use and configure the system as you wish. Create a image file of the system, just in case anything goes wrong in the future. This will safe a lot of time/work if you have to restore the system.