linux router and wireless router

[pokerface3]

hey people. i got a quick question, but first i got to explain how my network at home looks so its easier for u people to help
(i drew it myself )

this is my setup... besides the wireless part. that is what im here for. i want to know if it would be smarter to use a wireless router or a wireless card (im looking for wireless security)

is this setup even possible? if so then could u give me a quick explanation how to set it up properly!

 

[CrossCech]

Hmmm ... first question I have is: You're looking to have 3 different subnets? i.e 192.168.1.x, 192.168.2.x & 192.168.3.x? Or is your server issuing DHCP and you inadvertantly put the wrong addresses in for each client pc in your drawing? Should they be 192.168.1.1, 192.168.1.2, & 192.168.1.3?
Keep in mind that I'm under the assumption that the middle white PC you have in your diagram is a network server of some sort. What OS?
You'll need a switch in order to have your server do DHCP addressing for your network (and a 2nd NIC installed in your server). This way you'll have your 3 client pc's, wireless router (I can offer advice on how you'd configure your wireless router if you decide to go this route) and one of the NIC's on your server plugged into the switch. The internet modem you have would plug into the other NIC on the server. You'd lose the crossover (red) cabling in your diagram and go with all "straight-through" patch cables. This make sense to you? If not, PM me and Ill try to assist you in more detail.