ok its pretty simple then. Make sure your using DHCP and each machine has an IP address.
To get files from either PC you need to first go on the PC and right click a folder u want to share and hit "sharing and secuirty" and then enable sharing from that menu. From there go on your Mac and click the finder in your doc, then on the menu bar Go then Connect to server. From there you will either see the ips on your netowrk or you will have to type in the smb://computersip. From there u should be able to follow the dialogs and the folder will mount on your desktop.
If you want to take files off oyur mac. Go on the windows box and open the run command. From there type //mac'sip/macusername. It will open a few boxes that you will able to follow you will see your mac's home folder.
Hope this helps.