I have ~85 linial feet of cook books, around 400 books. I don't really bother with counting the magazines but I have all the Fine Cooking for at least one decade and every one of Cooks Illustrated since its original beginning [before it bankoed and Chris bought it].
I traveling now so I don't have allthe listing. I use the programs, Library Thing for ageneral listing of all my library and Eat Your Books for cooking books as well as actually finding something to cook in them.
Do I need them? No, but some are really fun reading.
May you eat well,