Hello! If your last laptop worked so well for you, why not try buying that again? I mean, it’s probably not that expensive anymore so you can afford to get a new one every two years. Also, you can upgrade it in a way that it can last much longer. Maybe get some cooling fans for it?
Or why not upgrade to a real surveillance system? It might cost less compared to buying a new laptop and upgrading it. And you’d get better quality too (most likely).