[Presto]

Share a folder on the PC. Then your Mac will be able to access it. Go to Finder > Click on the Go pull-down menu > Select Connect to Server. Then type in:

smb://servername/sharename

servername is your computer's name or IP address
sharename is whatever you called your share

You can also browse for it in your finder. It'll be under Shared, and you should see your PC in there. When you click on it, you should see your share.

EDIT: look at the video above. bingo.