wireless networking problem

hi

i have an xp desktop pc and a vista laptop. desktop pc is connected to a wireless router through ethernet. laptop has buitin wireless capability. both can connect to the internet. but i'm unable share files between each other. i've added each others ip address to firewalls trusted list. both can see each other on the network but cannot share files. what should i do. if you don't know please give the address of a computer forum. and since this a english learning forum please correct my mistakes and help me to put this problem in a more clear way. thank you