CompuServe Messages

The current issue of Mother Earth News has an article featuring late winter gardening with plastic sheet tunnels. I have the following questions: 1. What is the earliest I could set out tomatoes with this kind of setup? 2. There is a slitted type of plastic covering that I recall seeing in a Gardener's Supply catalog. Would that be better than solid plastic sheeting or would the cold present too much of a problem (I forgot to mention that I am in the Catskills in Upstate N.Y.)? Thanks for any light you can shed on the subject. Cynthia (she who counts her tomatoes before they're plucked)