I don't know how much you were joking, but...
I was joking entirely, but you're right. Some of that stuff, despite its obsolescence, falls under the law of supply and demand. There's just not much of it floating around out there any longer, so some of it is shockingly expensive when you actually start looking into it.
A CPU swap is probably more than he wants to deal with.
The most difficult part about dropping in a new cpu is finding the right one for your motherboard. Once that's figured out, a monkey could do this. Step one is to install CPUZ (be sure to run it as administrator) which will tell you everything you want to know about your current setup (motherboard make/model, RAM, CPU, etc.). Once you know what motherboard you have, you can figure out what CPUs your motherboard supports. When you figure that out, you can get a nice comparison between the prospective CPU and your current one here
. After that, there are a zillion videos on YouTube that will show you how to swap a processor.
But I'm thinking of trying a solid-state drive swap for his system drive. I've seen this article where you can supposedly clone your old drive/partition to accomplish this.
I didn't look at the article you linked to see what they recommended, but I always use Acronis True Image to clone drives. However, when you're going from a conventional hard drive to solid state, I'd recommend you consider a clean Windows (if that's what you'll be using) install. You might get better performance out of the SSD by doing so as opposed to cloning a Windows install configured for a mechanical drive. Also, there's just nothing better than a fresh OS install. But, yeah, a nice SSD usually makes a huuuge difference.