Breaking research indicates that -- gasp -- parenting books alone can't teach you everything you need to know about raising a child. In fact, your parents often are the best resource you can turn to since they possess the know-how and life experience to handle tricky situations. I know this goes against the grain of everything you thought when you were younger, but nothing brings reality into sharp focus like becoming a parent yourself.
Grandma might be a little bit rusty in her baby-care skills, but her instincts are typically right on the money, plus, she has years of invaluable experience to work from. Ask for her words of wisdom on every topic from diapering to feeding, and cherish every golden tidbit of advice she doles out. Sure, some things will have changed (babies don't sleep on their stomachs anymore due to risk of Sudden Infant Death Syndrome), but many of the basics are the same over time. Clearly, your mother and mother-in-law must have done something right if they were able to turn out two such fine specimens of humanity as you and your partner, right?