Butternut squash are of the hard shelled or winter squash variety. When purchasing Butternut squash, look for cream to yellow color,  6" long squash that are heavy for their size. The rind should be hard and smooth but not too hard to resist a thumbnail impression. There should be no bruises or soft spots. The flesh should be dark yellow to orange in color and is loaded with Vitamin A. The yield of 1 pound of squash raw is three 4 ounce portions. 

Butternut squash should be stored in cool dry areas of the storeroom, 42 to 48 degrees F. best with 70 to 75% humidity. Summer Butternut squash can be safely  stored for 2 to 3 months and winter Butternut squash can be stored up to 6 months without any loss of quality. Avoid Butternut squash that are soft or have bruises or mold.

Here is a list of Acorn squash recipes and other squash information:

http://www.pallensmith.com/features/recipes/wintersquash.htm