[kraft021]

You may omit nakaguro for objects of foreign origin. So, both パーソナル・コンピューター and パーソナルコンピューター are correct. However, it is not common to omit nakaguro for name of people.

For other use of nakaguro, you can use it like comma in English.
However, words you are connecting with nakaguro must possess same concept.

For example, you may use nakaguro for
食品・衣服売り場 (shokuhin, ifuku uriba) (food, cloth section)
In this case, both 食品 (food) and 衣服 (cloth) are 売り場 (section). (i.e. food section, cloth section)

You cannot nakaguro for sentence like 食品・衣服を買う (I purchase food and cloth.) because 食品 and 衣服 possess different concepts.
(i.e. food and cloth are different things.)