The number 1 thing I like doing with computers is..

taking old computers and making way better than they ever were

Case 1: My old laptop

sony pentium 3 — My old pentium 3 laptop (with upgradeable cpu!)

First things first

Windows needed to be reinstalled. For this I chose Windows 8.1 sincse it is basically Windows 7 but (most people deny this) more refined (and dosen't have that super annoying bug that prevent Windows from updating after a fresh install >:C), especally after you install OpenShell which returns the classic Windows 7 start menu in the more clean modern style

And Lastly

I install Kaspersky for a good and free antivirus then update driver with Snappy Driver Installer to squeeze out the most performace from this laptop and finnaly I install inSpectre which disables Meltdown and Spectre mitigations which cut the performace of older cpus like the one in this laptop litteraly in half. But don't worry the anti-virus will make sure these exploits aren't utalizsed