If the problem with your old laptop is just that the fan broke, you might be better off just getting a new fan. If you're near a big city there's probably a repair shop that will do it.

... although I guess 15 years is a pretty old in computer years. When my laptop died recently I went with a second-hand thinkpad for $300 (edit: not as old as I thought it was, it's from 2021.) But that was a year ago before prices for everything went crazy.