You have one interesting situation Charlie!
However, I'm rather for certain that out of the 30,000+ members here, someone should be able to guide you on you way! So, I'll give you my output on this situation to the best of my ability.
I think that if you live in a small town area, where there are no computer shops, then you have a good start. Mainly because most computer shops in the larger cities are hard to locate and there's a million of them, so peopel with problems have a tendency to spread out and thus your customers are going to tons of shops rather then yours.
If you're the only computer shops withina 40 mile radious, this is good, this forces everyone with a problem to turn to YOU, you have no competetion! Essentially within this 40 mile area you have what I would call a monopoly! Everyone HAS to come to you if they want to remove/fix their problems.
Here's somethign that I would do though. Go to a city counsel meeting, and ask if you can issue a poll. In this poll, ask everyone there if there was a computer repair shop, would they take their computer to it. If you can get a good enough average of people's opinions, then go for it. Make sure your target customers are aware that a computer shop might be opening up, and if one was to open up, would they visit it? Ask them various questions, if the results turn out to be in your favor, then open up the shop and get on with business!
However, you are a certified networking person, so, you may want to explore that option as well. Try applying at all kinds of places; such as Cisco, Sun Micro Systems, whatever kind of place you can find that needs someone to maintain and repair their networks. Remember, if a network goes down, their e-commerce goes down, so, they NEED someone to repair and maintain their networks, and seeing as how companies have multiple WANs, LANs, and VPNs, Networking Techs are CONSTANTLY being employed.
But hey, I'm just a kid, only 17, so my advice may be a little over the top, or just right. Take and do with it as you please. I just want to help out.