Setting up a network for an office enviroment that involves mutiples tenants?

I own a office building with 8 tenants, each from different companies and organizations. We want to provide free internet access to each client as a perk of the building. Each room is already wired with cat5 cable and leads to our storage room.

I was planning on buy a commercial high speed package and a router. However how do I prevent tenant A from trying to access tenant B's files. I know they can turn sharing off on their computer, but will that prevent them from accessing each others files if someone gets nosy? (someone local told me have one big router and then 8 smaller routers - one for each company - is that even workable or feasible)

Also should I go with static ips instead of dynamic? Any idea would be appreciated to make this work.

use a Layer 3 switch, IP routers are so outdated and limited in functionality. this way you can assign each tenant there own network address. you will be able to implement and manage the security settings from the switch.

go static, allows you to know who i which. I dont know about the file b accessing each others files, get firewalls, mcafee personal plus. Good luck,