The current consensus is that vitamin D levels should be normalised to maintain optimum muscle and bone health. The aim is for levels of 50-75 nmol/l. In order to do this it is expected that we need about 1000 I.U of vitamin D daily form supplements if we have modestly low levels. Obviously some people will be more severely vitamin D deficient and would need to take a larger amount in supplements.
The issue of additional calcium supplementation has also come up recently. It has in the past been usual for calcium and vitamin D to be given within the same preparation. However recent research has raised serious doubts about taking too much calcium as this was found to indicate a higher incidence of heart disease in the population studied. A reasonable assumption is that we need about 1000 mg of calcium per day, many of us obtain this amount from our diets and so additional calcium in supplements is unnecessary and may result in us receiving too much.