Assuming you have the two attached to the same Ethernet network...
Enable sharing on the PC, and then Command-K from the Mac. In a few moments you should see the PC's name come up as a server, choose it and log into it using your Username and Password on the PC (not the one you use on OSX). Then you have read and write access to your drive.
If you ahve a firewall on the PC, you may have to enable file sharing to happen.