I charge $30/hour residential and $50/hour business. Business rates apply mostly to server, database, bulk terminal sets, etc. I use what I call a CAP SYSTEM to cap jobs. How the cap system works is when I come out to do work for you, I quote you on the time a job takes based on the diagnosis of the problem. For example, if I quote a virus cleaning at two hours then you pay two hours of service and no more, regardless of the time it takes me to finish the job. Add on a very fair travel fee and you have an equally fair charge to fix your problem.
Travel Fee
  0 - 20 Miles: $10
21 - 30 Miles: $20
31 - 40 Miles: $30