My MoBo supports two CPU chips?

I was given a computer by a CAD company, and the motherboard supports two chips apparently. The chip in there now is a Xeon 5050. They said they most likely have another lying around, but my question is: will I notice a great leap in performance if I use two chips? It's a dual core with hyper threading, so if it works like I hope it does I'll have 8 cores with two chips??