I was told by my doctor to supplement vitamin D in my diet. I was also told that Magnesium is necessary for the body to properly utilize the vitamin D.

I bought a 1000mg vitamin D3 supplement and a 250mg Magensium supplement. It is made of Magnesium Oxide. Is there a better type of Magnesium I should have purchased or is this a good kind? I've heard there are a few to choose from and I want to make sure I didn't screw this up.