Lots to consider.
Is this primarily to be used a file server? Other requirements?
Will users work on files on the server, or download, work, and then upload back to server?
Use Ethernet if at all possible, to minimize network issues.
Agree with Mikael above. If you don't have a full time server guy to setup and maintain a Windows box, the next best thing, that will take less tech manpower and less cost would be a Linux-based NAS. Tons to choose from,
really need to determine the anticipated workflow, services required, how much space is needed (now, and for foreseeable future growth), and how it will be backed up.
Depending on space needed and internet connection, an cloud based sharing system is the most bang for the buck. If you consider hardware, labor, downtime risk, power, cooling, a UPS, backups, and security, patching, and on-going maintenance, not to mention replacing drives/server every 3-5 years....cloud storage is a pretty great deal.
