Unlike many other dried herbs and spices, dried ginger simply can not be substituted for fresh in most recipes. Fresh ginger offers a different dimension to many dishes that can't be duplicated with dried spices. Ginger will keep well in the refrigerator for at least a couple weeks. It can also be frozen for 2-3 months. If you are going to freeze extra ginger, I suggest peeling it first. Grating frozen ginger is even easier than grating fresh ginger.
When you are buying ginger, you do not need to buy a huge amount. Most recipes only call for an inch or two of ginger. Simply break a knob, about the size you need, off a large piece of ginger. (Yes, that is allowed. I actually was shown how it works by the produce manager in the first store where I bought ginger.)
Here's my tip for today. Did you know that you can peel ginger with a spoon? The skin is very thin and just rubbing the tip of the spoon across the ginger removes it easily. Once the ginger is peeled, you can slice it into disks, create matchsticks or dice it fine. A microplane works great to finely grate or mince it as well.
Here are some recipes with fresh ginger: