[villagetinker]

I just upgraded the wifi on my computer, and the 5G wifi in my house now shows just under 300meg, wireless.
Just a point of clarification to your plan, you can have the Xfinity cable modem in the house provided you actually have cable to the location. You can also use the properly terminated Cat5 cable to get back to the garage. At the garage you will need to install a router, and the properly terminate the other Cat5 cables. Finally, you will need to replace all of the cover plates for the new Cat 5 outlets and the properly terminated Cat 5 cables. Then you may need to run between your various rooms and the garage to check that this is all workings. I looked at this for a few minutes, and decided wireless is much easier, just my humble opinion.