At the risk of being called a corporate bootlicker, it sounds like it isn't their own, it was their employer's. If it's your own, absolutely, fair play. If it's your employer's... Then it feels murkier. I wouldn't blame their IT department for being quite cross if/when time comes to upgrade and return the laptop and give it a second life. For example, I would be quite pissed if IT gave me a defaced laptop like this as a loaner while mine is getting repaired.