Workgroups

The Network tab handily replaces what XP used to call 'View workgroup computers', except that Workgroups are no longer any real issue, as Vista simply ignores them for the most part, and only the network your are connected to matters. The only reason that workgroups are left in is for backwards compatibility, so if you're on a network that contains PCs both on Vista and on XP, then you'll still have to make sure all the computers that you want to see one another are on the same network.

To change your workgroup on Vista, use the following path:
Start Menu > Control Panel > System and Maintenance > System.
Then under Computer Name, Domain, and Workgroup Settings, click Change settings. Once you're past UAC, then simply click the 'Change' button, and rename your workgroup. Easier than it sounds, I promise.

Another useful feature I've found on the Network tab is that your router will show up as a connected device on your network, allowing you to directly access it, as opposed to having to use a manager, or put its ip/name through a browser to get to it.