Cant use sharing on secure wireless network
 

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