Cant use shared folders on secure wireless network

[kiaconcepts]

I have three pc's Two are hard wired and one is wireless, I cant connect to my wireless pc unless the network is unsecured I want to be able to use my network secured and still be able to use sharing, and printer, My router is a WRT54GS, and the wireless PC is using A WUSB54GP..
Also have another question, I am unable to use remote programs like
Radmin and TWD remote Anything, why is this?? Any help would be great, Thanks

[sniper]

what do you mean by unsecured ? do you mean without wep or wpa or without a firewall ? , either way if it works without one of these then one of these is obviously where the fault lies . can you go into further detail