My folks did a pretty good job of keeping our family supplied with food using a 1/4 acre of land. I'd say 65% of the fruits/veggies we had growing up came from our garden. The meat came from the surrounding woofs, fields, and lakes. I remember spending days in the fall canning stuff or freezing it, depending on what it was. Sidenote: the only power tool used was an old rototiller. Every peice of waste plant matter was composted, and we used sprinklers and rain water to keep everything hydrated. This was in central Minnesota. The soil was great but the summers could get dry.

I don't know about meeting all the needs of a family, but I think if you are willing to put in the labor you can make a good dent. I'd STRONGLY reccomend taking full advantage of your local Master Gardener's group.

-Blast