For a NOOB...
Does RDC only work for computers on the same network? I want to be able to connect my iBook @ work to a PC @ home...
Yes, you can use RDC from anywhere but you might have some stuff to set up.
First, you'll need one of the following operating systems. Windows XP Pro, Windows XP Media Center, Windows Vista Business, Windows Vista Enterprise Windows Vista Ultimate, Windows Server 2003. All versions of Windows starting with XP Home come with the client, similar to the free Mac version. I'm not sure if you can connect to a user if it doesn't have a password.
In XP, right click "My Computer" to get to system properties. From there, click the "Remote" tab and then check the box to enable connecting to this computer remotely. You might need to add users to the list. Your current user is automatically added.
In Vista the process is similar. Right click "My Computer" to get to system properties. I think Remote Settings is on the left side of the window.(I don't remember, I may be wrong about that.) Once you find the remote settings, click the radio button for the less secure connection. You might need to add users to the list. Your current user is automatically added.
Second, do you have a router? If you don't, I don't think there's much to do. You might have to enable port 3389 in your firewall. If you do have a router, you'll have to open up port 3389. This site
http://www.portforward.com has some good guides for that. Just go to the home page, click "common ports", find "Remote Desktop" and then look for you router model. As an example, here is the guide for setting up RDC with the Linksys WRT54G router(version 5 and 6)
http://www.portforward.com/english/routers/port_forwarding/Linksys/WRT54Gv5/Remote_Desktop.htm
Once you've done that, go to the client and ...
If you're at home on your network, type your computer's IP address in the box.
If you're not at home, type in your external IP address in the box. It's on the PortForward homepage.
I think that's it.
Hope that helps.