even though it can have a greater expense attached to it (with trunking, the cables and patch ports) I would highly recommend using cable. It is more reliable and secure for your business.
I would also recommend seeking a local company that can help with this as depending on what you wish to do with your network will greatly determin the level of knowledge that you would need to acheive this.
For basic internet you would need a router and a switch with enough ports to allow all of the cables to get a connection. After that if you're unsure seek external company to help.
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A healthy mix of both wired and wireless networking would be the most flexible solution
For wired, as mentioned, you will need some sort of routing (Layer 3 switch, router, etc) and 1-2 switches for your users and other end devices.
It is possible to cable the desktops, printers and other "stationary" devices into either cable drops to them - or, if you go a bit more professional - wall jacks that wire into a patch panel or 2
For wireless, 1 - 2 WAPs (wireless access points) at - for example - opposite ends of the office would allow for connectivity of laptops, smart phones, Tablet PCs (iPads, Android tablets) for your users, clients and guests
Best answer in any IT environment: "It depends". It is reliant on what you want to do, what you need to have and how much time and capital you're able to invest in it...
Cable will be the way as it is more reliable. well items that you will need will be modem router (for internet), switch (about 24 ports) and if you want to have file sharing you can have a NAS (size depends on you) and actually the list will go on.
I agree, cable is the most secure. However i would not advise getting just the 1 switch. Switches cause bottle necks. (Called collision zones.) Imagine a car park with a 1 lane exit/entry, the cars have to queue to get in and out. The more cars (devices) the longer the wait.
On a switch, when 1 computer is sending data all others have to wait, this slows everything down. You will soon get users moaning about slow computers, when it is actually a badly designed network, causing the delays.
I prefer several routers and switches, strategically placed. The routers will be the LAN gateways for each computer department, finance, purchasing, stores etc. and the switches will connect the computers and printers etc to the router. The routers are the key devices.
A company that can design the network will be better able to suggest a solution, as it is very much an on-site job to assess what you need. Placement of the devices, how to run the cables etc. are things to take into consideration when planning the network.