Not with that gear so let's try this feature CLIENT ISOLATION.
http://www.newegg.com/Product/Product.aspx?Item=N82E16833122045 supported multiple SSIDs and the all important feature you need. Ready?
-> CLIENT ISOLATION.
I have two linkys wrt54g wireless routers and in a situation with a renter that I would like to have two seperate networks. I have multiple computers that I do file sharing between along with a ethernet hdd hooked into the router for backup of all comps. I experimented by hooking routers in series and giving out unique ssid's. I seemed to get things working all accept the internet through the second router. Any suggestions on how to accomplish this would be great.