For full access to your Mac from the PC do this,
open System Preferences and go to the sharing pane, turn on windows sharing,
OK, note the Accounts button, underneath it it gives you the string with which to set up from the PC side.
Go to the PC, Network Places, add a new one, don't let it browse, you want to tell it manually, enter the address \\192.169.x.xxx\yourusername and hit go.
Wait a bit 30 seconds and you should get an authentication dialog on the PC, enter your credentials and your done.