I have really enjoyed the two books by Cassandra Danz (aka "Mrs. Greenthumbs"). They are hysterical (she's also a standup comedian), friendly, and make you want to play in the dirt immediately. Plus she has lots of excellent tips for the beginning gardener to take the pain out of the experience. She'll give you an easy way to avoid double-digging (yuck-o-rama!) by preparing the ground with a covering newspaper and mulch.
Have a great time!