Do you have any experience? I doubt anyone has ever really stumbled in to their "dream job" especially in IT with little or no experience. Chances are, unless you live in a very remote area, there are places around that need entry level helpdesk/tech support. My advice is to do that and gain some experience, feel your way through different aspects of the business, get some certifications in the mean time, then maybe (if building PC's is really your dream job) eventually jump on board with a big name manufacturer building show PC's or setting up PC's for gaming events & shows/LANs/competition
But like USAFRet said if you enjoy building PCs for yourself, friends, whatever, in the comfort your own home: getting paid to do that is going to be a drastically different atmosphere, assembly line style