Hey /sci/, I can recently came into possession of my grandmother's old computer. It's pretty shitty (see pic), but I'd like to maybe turn it into something that could run long simulations on the side.

I want to give it more procession power (add more RAM?), while also upgrading it from Windows 7 (or potentially something else) as cheaply as possible. As you can probably I don't know what the fuck I'm doing. Any anons here with any experience in this kind of shit that could give me some advice?