I have used Airborne in the past with good success... if my coworkers (we don't have cubicles, but lined up desks, so we're all exposed) get sick, I'll use it every day....
The last time I felt something coming on (around here everyone has had that high fever, sore throat, chest congestion thing - I WANT NO PART), I got those 10 calorie vitamin waters and also drank OJ. I was just starting to feel the swollen glands and the start of a sore throat, and drank two V waters and some OJ... then the next morning did the same thing... by the following morning all traces of cold were gone!