Is it worth upgrading my pc or just building a whole new rig?

Hey guys, I've recently had the urge to start gaming on pc due to the huge graphical improvements in the pc versions of games. Now I've come across an Acer Predator AG5900 (got it for free) it runs fine but I haven't tried any games yet because I know I won't get the performance I want.

So my question to you guys if I should invest in upgrading the Acer or if I should just throw the money into building a new rig. If I should upgrade it a list of what I should be looking to upgrade would be great as well. Thanks if you took the time to read this!