If you ever find yourself emailing docs to the computer in the next room so you can print them, HomeGroup was designed for you. You can easily connect two or more PCs running Windows 7 on your home network to automatically start sharing printers - your Pictures – Document and even your Music, with other people in your home. Share everything you want all around your home, using the connection you have to your router (broadband modem) this can be via WIFI or a cabled connection.
A HomeGroup is a group of computers on a home network that can share files and printers. Using a homegroup makes sharing easier. You can share pictures, music, videos, documents, and printers with other people in your HomeGroup. Other people can't change the files that you share unless you give them permission to do so. You can help protect your HomeGroup with a password, which you can change at any time.
When you set up a computer with this version of Windows, a HomeGroup is created automatically. If a HomeGroup already exists on your home network, you can join it.
After you create or join a HomeGroup, you select the libraries that you want to share. You can prevent specific files or folders from being shared, and you can share additional libraries later.
Computers must be running Windows 7 to participate in a HomeGroup. HomeGroup is available in all editions of Windows 7. (Windows 7 Starter and home basic edition cannot create a HomeGroup but can join one).
For help on setting up a HomeGroup network Microsoft provide a demonstration video at the link below.
If you have another version of Windows (XP or Vista) then Networking/sharing is still possible across a network but it requires a little more knowledge to setup and use.
For an easier to use sharing interface for Windows XP and Vista you could try Network Magic, the Basic version is free (includes 7 day trial of pro, The basic version is free and you do not need to pay unless you want the extra functions you get with Essentials or Pro).