i agree with subskull--i have Zicam in my bag right now. (Greg, if you're coming home for Easter, I'll be home tonight--give me a call and you can borrow some!)
if you're going to buy it, you should get the nose spray--i have the mouth spray and it works the same but tastes crappy. Zinc stuff is the ONLY thing proven to shorten the duration of or prevent the onset of the common cold. my roomie's mother uses it constantly and she hasn't gotten a cold since she started.
it is pricey, though. $14 for a little bottle.