If you can remember what you did before the problem came up or any error messages DOS gave you, it makes the nerd's job that much easier. If it isn't a disaster recovery situation, try to solve the problem yourself first. If your nerd knows you only call when things are serious, you'll get a much better response. Don't play the field. Nerds are delicate social animals, and if your nerd thinks that you are getting computer fixes from other nerds, you'll hurt it's feelings.
Nerds respond to praise much better than criticism.