Both methods are acceptable.
A stock made with roasted bones is called a brown stock. A stock made from raw bones is a white stock (or sometimes just stock).
Practically, it's very difficult to get a true "white" stock with beef, as opposed to chicken, since all of the impurities will darken or cloud the colour - but that is semantics.
Brown stocks have a richer flavour, but that does not automatically make them better - it depends on what you'll be using it for. For soups, where the stock will give most of the flavour, brown is generally preferred; however, as a "flavourful liquid" to use in sauces, risottos, etc., a white stock may be more useful because you don't want it to overwhelm the other flavours.
One cautionary note: Beef bones tend to give off a lot of what looks like blood (actually myoglobin) when boiled. If you're trying to achieve a perfect clear stock (white or brown), then you may want to blanch them first; dump them in the pot, bring the water just to a boil, then dump out everything and start over. You really won't lose much; most of the proteins are deeper within the bones and requires several hours of simmering to extract and denature.
If making a brown stock (from roasted bones), do this after roasting, not before. It will also help you to get rid of any excess oil so you won't need to skim as much.
According to the Culinary Institute of America their basic formula for all Meat or Poutlry based stock would be:
8 lb/3.63 kg bones and trimmings
5 -6 qt/4.80 - 5.76 L water
1 lb/ 454 g Standard or White Mirepoix
You would not need any actual cut of meat for a stock according to them. Those would be reserved for making a broth. Their basic formula for broth doesn't specify a ratio between meat and bones just 10 lb. of meat or poultry including bones to 5 qt water. If you are converting a stock into a broth they give the formula of 3 lbs meat to 5 qt stock. Based on that a good starting point might be 7 lb bones and 3 lb meat to 5 qt water.
Just an FYI they make all their mother sauces using stocks, broth seem to be reserved for soups and other applications.
Best Answer
You can use it as a base for risotto if you like the flavor. It will make lovely pink rice.