Watch the lighting
As you're taking pictures of smartly dressed guests, fancy dishes, and horns of plenty, don't forget about the lighting. Few lighting situations are trickier than Christmas morning, as an array of lighting sources compete to confuse your camera. At the same time morning sunlight is streaming through the window, room lights may be shining overhead, decorative bulbs might be blinking on the tree, and perhaps even a couple of candles may be flickering nearby, overwhelming your camera's sensor.
Your best bet is to set the white balance manually using a white sheet of paper, before the festivities begin. Check your camera's user guide to see how to adjust white balance. Try increasing your camera's ISO setting, too. This control--which affects how sensitive the camera is to light--is usually best left in its lowest position. But rather than relying on the camera's flash, try increasing the camera's ISO to 400 so that you can properly expose your pictures in the limited indoor light of a winter morning. Another solution is to put additional light sources on your subject: I like setting candles near people because they cast a warm, flattering glow onto faces.
When you finally get your pictures onto the PC, you may find that not all of them turned out as planned. Use an image editor to remove any red-eye, which you may have a lot of if you used your flash, and to reduce digital noise, which can happen when you shoot with a high ISO.