At what point is my cold no longer infectious?

Someone recently told me–somewhat authoritatively–that as long as I’m still blowing my nose, I’m still infectious. Is this true? I was under the impression that you’re mainly infectious early on, that is, within the first day or two of the cold really manifesting itself. This past Monday was the first I noticed cold symptoms; today I’m still a little runny and my throat has a *very * light tickle.

The crux of my question being-- do I still have to stay away from my adored godchild, who I think gave me the damn thing in the first place?

I’m not sure about colds, but I’ve heard that some ailments are already not infectious by the time you know you have them. It would seem to me that colds–on the otherhand–spread primarily by hand contact (doorknobs, etc.). If you sneeze into your hand or use a Kleenex that spreads particles onto your hands, and then you go into a room using the doorknob, then the next person to come along, touches that knob, and uses his/her hand to touch a mucous membrance, they’ll get your cold.

But then again, I’ve had chest colds that lasted weeks (the coughing part), and the doctor told me that the infection was gone, and it was just irritation that made me cough.

“Colds are most contagious during the first 2 to 4 days after symptoms appear, and may be contagious for up to 3 weeks.”

From here.

Thanks, guizot, WhyNot. Appreciate it!