With a Mac running OS X and a PC running Windows 2000/XP, you can easily share files between the Mac and PC. You can connect the Mac and PC using Ethernet cable directly (Note: you can use a straight cable to connect both machines, and there is no need for a cross cable.

To access PC files from a Mac, you need to enable File and Printer Sharing. You also need to create created a folder to share. To connect to the shared folder, select Go from the Finder menu and click Connect to Server. You should be able to see the PC name displayed. Select the PC and click Connect. You will be prompted to enter the credentials to log on to the PC (domain/workgroup, username and password). If the connection is successful, you will see the share icon and browse the shared folder.
To access Mac Files from a PC

With Mac OS 10.2 or above, you can use Windows’ My Network Places to view the shared folders on your Mac. To do that, you need to enable the Windows File Sharing on your Mac and check the Allow users to log in from Windows option

How to enable Windows File Sharing  On Mac

• Open System Preferences - Sharing
• Make sure the Services tab is selected
• Click to check Windows Sharing
• Note your Mac's IP address at the bottom of the window