The easiest way:
Right-click on "My Computer" and select properties (On each computer)
Once the next page opens up, click on the tab that says "Computer Name"
Click on the button that says "Change"
Type a unique name for the computer. (Each computer must have a different name)
Type a workgroup for the computer (Each computer must have the SAME workgroup)
Afterwards, you have to reboot before it will take effect.
Once your computers come back up, you should be able to go to my network places and see the other two. You're not finished yet
Now, you need to select a folder on each computer that can be shared.
Also, whatever computer has the printer attached to it, you need to share it.
You do this by right clicking on the folder and printer, select properties, and share them on the network- you may get some security dialog that informs you this is dangerous
Now, when you look for the printer from one of the other two, you browse the network to find it, and once found, it will install the print driver for the printer of the machine you are connecting too.