I know I posted in the yes side, but there is more to consider. Can you take care of the child? Will you love it, and will it love you back? With this said, I would find it hard to adopt a child of another race, just because I wouldn't want the child to have to ask questions like "Why am I different?" It would also bring up questions from others like why my child is a different race when both of his or her parents are white. It shouldn't matter as long as you love the child, but it would bring a few extra difficulties to raising the child.
Children above all want a loving home, but if there is a choice, they'd usually like to look something like their parents. So if an Asian child can find an Asian parent or a black child a black family, that would probably be in the best interests of the child. However, love and support should be the final determinant.
A parent or couple should be able to adopt who they want, and if the child is old enough, who they both want to be with. We really need to stop caring about the color of someone's skin, or hair, or the shape of their eyes, or their height, or anything. Should a child not be matched because the child has straight hair and the parents have curly hair? NO! Race does not matter.