Disk Array or NAS for a startup business

I am trying to start a a small video editing service from my home. At the moment I have a W2k server and 2 work stations running on a small network. I also have 3 HDD ranging between 80GB & 120 GB in size that I would like to add into the network in either a small disk array, or as NAS. What is my best solution, budget limitations being a very large factor in the equation