Charles wants to run the new Microsoft Flight Sim on his computer, but it can't handle it. Can he upgrade the motherboard and CPU and will that be enough? Leo says that the new sim looks nearly as real as real life. Smooth and realistic. Flight Sims are really high end and even the minimum requirements that Microsoft suggests are probably not good enough.
You'll at least want an i5 processor with 16GB of RAM and a better video card with 4 GB of VRAM. Leo suggests AMD, and a GeForce 970 video card. So you'd want to replace the motherboard, CPU, Processor, and probably the hard drive. So you may as well just get a new computer. It'll probably cost less or at least be easier to support. And since Charles' old computer is a Gateway, he'd have to find a motherboard that can fit the case, which could be a challenge.
Check out NewEgg.com for their bare bones systems. Then you can add to that as you can afford. It's going to be a lot easier than trying to upgrade your old machine.