Federal Law prohibits spying on US Citizens without the express direction of a court order. And this is generally reserved for terrorism cases, drug trafficers, child pornographers, organized crime -- you get the point. ISPs and telecoms are specificallly prohibited from targetting and exploiting customer information stored on their systems.
That being said, most IT companies have tens of thousands of customers. The off-chance that any one of their employees, during the course of their regular job, is going to accidentally pull up and "research" into your personal files is exceedingly small. And even if they did, in the position they're in, they've seen it all before. Many, many times.
Generally, IT professionals will only look into personal files AT THE REQUEST OF THE CUSTOMER (to fix problems etc). So, be aware of what you're asking for - you may get more than you bargained for.