I'm writing to you from a late 2008 MacBook pro - 8 Gb RAM and SSD
1. I have mac os High Sierra, using a method to install on unsupported macs (just google it).
2. It supports Windows 7 via Bootcamp and I've made the upgrade to Windows 10 (keeping Win7 drivers).
All works. Not great, but works.
I've also opened the case and changed the processor paste.
So, the best way to keep an old MacBook alive is... actually Windows!