I believe the Pro key used in Anytime Upgrade will completely replace the HP activation. When you then install HP on the netbook, you will be referred to an Activation robocall which updates the hardware signature associated with that Product Key. A recording will ask you if you only have that product key on one computer. When you answer correctly, it will update the hardware signature in MS activation computers so that any other machine's use of that key will be deactivated upon connection to the internet.
Only if the underlying use of HP as the launching platform for the Pro Anytime upgrade still somehow maintains HP activation would this deactivate your Pro install. This is fairly new ground for us here as we only confirmed in recent months that retail keys work in Anytime and related issues have not been completely sorted.
In the worst case where the HP key maintains activation as the base of your Pro install, you might have to do the workaround which allows an in-place Upgrade between versions of Windows 7, to avoid having to do a clean install of Pro. This definitely resets activation and says bye-bye to HP.
Once you have it set up running as you like, make a Windows 7 backup image stored externally so you can reimage the HD or a replacement instead of having to reinstall. Backup Complete Computer - Create an Image Backup