Apart from the above given suggestions, when the technician comes next time (since, I think that you won't be terminating his services immedietely), ask him to provide a permanent cure for the Virus Trouble. Also if there is some sort of OS corruption, ask him to show you how to take image of the working OS, and restore it when the OS gets corrupted.
You can have licensed version of Norton, Quick Heal etc. ( since you are paying money for it, the company reps. will do the tech. work for you) and get peace of mind.
Getting free AVs will save money, but then you won't have customer support and will have to do almost everything by yourself.
Arguments are for both sides, decide what is your priority (Budget or Ease).
GA