Installing Chrome OS on older Intel MacBooks and iMacs is pretty easy to do, not to mention that it is free. Slapping the modern yet low demanding software of Google gives a new life to your old Apple ...
My wife as an older Macbook (3,1 I believe) that has a few odd problems and I think it would probably benefit from fresh OSx installation. While I'm at it, I'm planning to throw in a larger hard drive ...