I assume you want the wifi network on seperate subnet to the wired lan?
This would depend on whether you router/switch was vlan capable.
Certainly on my cisco router the wifi is on a seperate vlan, as is the dmz, the server lan etc with all the traffic between vlans contolled by a zone based firewall.
I doubt a comsumer grade device would have this functionallity to be honest, but having never had a linksys, I cant say for sure.