I use F- secure antivirus, and some windows firewall. I`m also behind unis`s router and security stuff, so the pc should be protected. But if he has placed something on my pc with my own accesscode it might be a problem.
Come to think of it, my pc did a virus scan once a day earlyer, after he had used it, the scanning stopped, it still says its enabled...and says its updating every day, but i dont see the scan anymore... yelp!