What's the difference between resource heavy or light software and does it affect computer longevity?

One of my laptops is a very old (IBM Thinkpad T20 2003) and I'm trying to make it last as long as possible. I don't have it connected to any networks, including internet, since I heard that that is a big drain on resources. I also keep it as cool as possible during most of the time it's running. I'm wondering if resource heavy software apps such as iTunes, Photoshop, ect. have an affect on laptop longevity. Lately I've been switching to mostly portable apps that are reported to leave a lighter footprint (VLC player, One by One player, Irfanview photo editor, ect.) So I'm wondering since these programs don't make an impact on the registry would it help extend the life of the laptop.