Not Powerbook or MBP specific but...
On the PC, right-click a folder or volume and select Properties. Go to the Sharing tab and set options.
On the Mac, you may be able to connect directly using the Network icon in any Finder window once sharing is enabled on the PC. If not, from the Go menu in the Finder, select Connect to Server. Type in smb://<ip address>/. You may have to add C$ after the last / to indicate connecting to the PC's C drive. To get the IP address on the PC: Control Panels->Network Connections->open the connection you are using, either wired or wireless->Support tab.
Steve