How do I connect to a PC over Ethernet?

MacOS X 10.1 & 10.2
Follow these steps to connect to a PC via SMB (the Windows network protocol):
1) In the Finder, choose Connect to Server from the Go menu.
2) In the address field of the Connect to Server dialogue, type the URL using this format (see below for info on naming conventions): smb://ServerName/ShareName/
3) Click the Connect button. It may take a few seconds for the connection to be successful.

You will be prompted for the workgroup, user name, and password. In addition to connecting to actual Microsoft Windows computers, you may also use the Connect to Server dialogue to connect to a Macintosh that is offering Windows File Sharing.

The ServerName maybe an IP address or DNS name. The ShareName relates to the shared disk, volume, or directory, and it must be specified. Note that you cannot use spaces, instead type %20 in it’s place. Nor can you have hyphens in the ShareName, you will have to remove it from the actual folder or disk name. Example: smb://192.168.0.2/shared/ or smb://MYPC/shared-data/

The name that appears for an SMB sharing Mac OS X 10.2 computer will be its DNS defined name if DNS is available on your network. You may not recognise the DNS name. The user-defined computer name only appears for SMB when there is not a DNS entry for the computer. See your network administrator for questions on DNS service.

On a final note, MacOS X will not allow you to connect to two or more SMB volumes simultaneously, as this will cause a Kernel Panic (a crash) to occur. Do it one at a time.

MacOS X 10.3 'Panther'
I’ll attempt to explain, briefly how to connect to a PC using MacOS 10.3. Here’s a checklist you will need to run through in order for you to connect up to a PC’s hard disk:
1) You’ve setup and plugged in the ethernet cables between the two computers, or setup a mini network which may include an ethernet switch or hub, a network printer and fast internet connection via a ethernet modem/router.
2) Make sure that the PC has sharing switched on for either folders or the whole hard disk.
3) Switch on ‘Window Sharing’ in the Sharing window, within OS X’s System Prefs pane.
4) Now to have to make sure that your Mac and the PC are using the same Username & Password that you use to log-in to your OS X user account. Eg. username= mikehutch and password = windows, so that when the password window appears when connecting to the PC’s hard disk via the Go menu and Connect to Server... menu command, you type those two into the appropriate fields and voila, you’re connected.
5) Setup permissions for the folders, so that only a handful of selected users can access it.
For full details of everything you’d like to know about networking go to: www.apple.com/support/panther/network/

MacOS X 10.4 'Tiger'
Networking between MacOS X and Windows Vista is pretty much the same as in MacOS 10.3, except for 1 or 2 slight differences, it'll be better off if I show you how to connect to a PC with a ordinary Ethernet cabled network. See these picture guide pages: MacOS / Vista.