Since you said "old windows PC", does that mean the current OS has been installed long time ago and already connected to internet many times? If yes, people usually don't count it as airgapped PC. At least, you should format the storage, reinstall the OS and install other necessary software (such as wallet software) and never connect to internet again. And it's recommended to remove networking component if it's possible.
And will it be possible for an hacker to install those drivers remotely?
No, in first place the hacker must connected to your PC.
the victim could have downloaded a dodgy wallet.. (meaning no need for hacker to connect) before the victim removed network card/drivers.
whereby the dodgy wallet signs transactions but to a known set of a scammers addresses. so when the victim transfers the signed tx in hex/byte format. the victim wont know the receiver address is the scammer. and the scammer didnt need to connect to the victim