Computer builds :
Yeah I've definitely heard of that, but if possible I was going to try and go wired as I currently experience about half the download speed on my laptop compared to the PC connected to the router which is connected to the modem. You ever hear of MoCA? I was thinking maybe something like that, or I could always try to run an Ethernet wire from the router to the new PC. A 2nd modem would cost double right? Thanks!
An Ethernet cable should be your first choice if you can possibly manage it. It just takes some planning (and maybe a bit of ingenuity) to find a good route from room-to-room. If it's difficult to bring the cable down inside a wall, you could consider bringing it through a small hole in a closet ceiling to help keep it somewhat hidden.
MoCA is also a good choice, but you'll want to be sure the coax is in good condition. It should run on the same cable as TV, but if you have extra cable in each room, you might try to keep it on a separate run.
There are also powerline network adapters, but they tend to be hit-and-miss in terms of performance.