Sure! Haven't you ever been frustrated with the people who work at the local electronics shop? If you've built a car computer you've got a leg up on most of them!
Don't underestimate yourself. If Fry's is looking for more than you have, start with some place like Circuit City or, if you must, Radio Shack. And don't bull****. You don't want to work for somebody who doesn't want to hire you based on who you are and what you know (and can learn).
(burger king -> construction -> cell phone installer -> cell tech -> computer tech -> lan admin -> tech support manager)