I was adding a 512MB

Question

I was adding a 512MB card to a Compaq Presario that has an ASUS K8S-LA (or Compaq motherboard: Salmon-GL6E) and discovered what looks like a heat sync loose inside the case. I can see where is was connected to a part of the board that is next to the large CPU Heat sink. What is this part and how does if effect the motherboard? How do I reattach it to the motherboard?