My Dad was using some dust ridden Pentium 4/GeForce MX 440 "custom" build from 2002. You could barely scroll in a web browser. I went to dust it out when I noticed the capacitors on the motherboard were leaking! It was far more cost effective to just build him a new rig. The AMD build is plenty fast for my Dad. He does basic web browsing, occasional gaming like the original Max Payne, and music editing.
I tried out Half-Life2 just to check, yes it's an older game. Max settings, 60fps, smooth and bright.
I bought a new case from a local retailer, so that would add about $30. I also added a front USB 3.0 panel so he wouldn't have to go crawling around in the back.
He is pretty happy with it. As long as he keeps it dusted and free of spyware, he will be happy with it for a long time.