I love to use butter in cooking and baking. To me, it tastes so much better than margarine. The problem with butter, however, is that it is very hard when you first take it out of the refrigerator. That makes it difficult to use in recipes which call for softened butter, particularly cookie recipes. When I am short on time, I will microwave it for about 10 or 15 seconds. If you aren't careful doing this though, sometimes it will be too melted, which will make your cookies flat.
I found a cool idea in 101 Cooking Tips, a publication which I have referred to previously. When you remove the butter from the refrigerator, open the wrapper and slice it up. Then leave it out at room temperature for about 30 minutes. It should then be the perfect texture for mixing into a recipe which calls for softened butter.
So have fun baking!