I don't think you can claim Dell is a Monopoly. Too much competition.
There's quite a few of the M&P Stores in S.FL (to add to the list). I think the question would be do mom and pop stores compete with Dell (and IBM, and Gateway, and HP/Compaq) on Price? And the answer is, if they do, they are probably scamming the customer in some form(just a hunch).
So you don't want to use those guys as proof that Dell isn't a monopoly? Why exactly?
What about places like MWAVE, NewEgg, and GoogleGear(with it's new name), with good customer service and great prices? They certainly compete with the big guys. Many folks here buy their parts from them and build their own systems instead of using Dell.
Mom&Pop stores are left being niche shops (service/convenience) mainly. But there IS a potential to build on that. Dell started out as a small operation out of a garage, IIRC. It just takes luck and hard work how much of each is left for you to decide.
I'd have to say the PC business is one of the most competitive businesses there is. And that's why it's difficult for a Mom&Pop store to succeed.
I think you should focus on something else...