|Connecting by wire is more reliable, faster and more secure.|
On a wireless router, you can get in trouble, because of some wireless network cards, that do not work with any wireless router as expected. Also all the wireless connected devices must share the bandwidth of your wireless router. BTW, I've never seen a wireless N router with 300 MBit/s, that really worked on that speed. Mostly you get 50 percent (150 MBit/s) and that has to be shared by 3 computers and 1 server. If there is a copy job running on one computer, mostly the rest has no access to the network until copy job has finished.
Server should always be connected by wire.
Also if there are electro-magnetic influences, your wireless network may not work or gets incredibly slow.
Walls and woodpanelling may couse your wireless network not to work on all places in your environment.
Router setup differs on what router you plan to use.
Cisco routers for business are more complicated in configuring.
In a such small network environment as you described, a SOHO router will do.
But I would suggest to use wired connection. Therefore, you can buy a small Gigabit switch, where all computers are connected to, and a router, that connects you to the internet.
I guess, all the computers you have, do already have a gigabit network card installed.
MAC address filtering:
It's normally just easy going. In the routers setup, the already connected computers are shown in a list with it's ip address, name and MAC address. You can pick up one to add it to the exception list. So no one has access to your network, except the computers in the list.
Here is an example on how to configure a Linksys Router with WPA2 and MAC address filtering.
The routers do have a build in firewall.
Every computer should also have installed antivirus software.
I prefer to also install a personal firewall on every computer in the network. Most of these firewalls includes an application firewall, where you can allow applications, to be started or to communicate with the internet or not.
If you first install the antivirus software and the firewall and then install the applications, you plan to use, the firewall can learn, which software is installed and should or should not communicate with the internet.
The original poster should always write the last response !!!
Let us know, if the problem is solved !!!