Can someone see what I did on my PC?

I'm not worried about bugs and spy viruses. I'm curious if anyone could see what I did on my PC, what pages I visited etc. (even if I deleted cookies and history) if he was a repairman or something like that.. Our shared computer used to break out really often so we had to reinstall Windows and the whole operating system. If it happend on my laptop, would the person who repaired had informations like this?