Every local small town computer store that I've ever seen was eventually destroyed by the price competition from the big computer companies. You can't get the same volume hardware and software discounts that Dell and Lenovo do, so don't even bother trying to make a living just by selling computer stuff.
Most of the big computer companies suck at local support, though, so that's your niche. Just keep your rates a bit lower than Geek Squad and get some good references, and you'll be good to go.