Hi L.~
My first thought after reading your post, being an allergy sufferer, is that perhaps your daughter is suffering from allergies, rather than frequent colds? I don't know how common or unusual it is for a child to have as many colds as you describe, but it does sound like sort of a lot, especially in light of the fact that she does not go to school or daycare. But I am no expert, only speaking from my limited personal experience as a mom... :)
There is a website that I refer to almost as much as this site for info. :) It is a site run by a family of well known and respected pediatricians, the Dr. Sears's.
www.askdrsears.com
Here is their article on Allergies, and it provides a wealth of info about allergy symptoms, treatment, etc., and compares allergies to colds.
http://www.askdrsears.com/html/11/T080500.asp
If after reading that article, you think your daughter may have allergies, I'd talk to her pediatrician about consulting a pediatric allergist.
There is other info on this website about colds, how they occur, how to treat, etc. On the homepage, go to the Childhood Illnesses section at the top, then click on Colds, Coughs, and Sinus Infections. Lots of info there too. Basically, the whole site is a wealth of info on just about any topic a mom could need to know something about.
Just as a side note, my allergies are as bad in winter as during the "pollen season" because dust drives my allergies mad, and being cooped up all winter wreaks havoc on me...
Hope this helps you get things figured out!