This is a little guide I wrote up a little while ago. Look under the section about Networking with a hub or switch, and start at point C) that talks about workgroups. http://forums.amd.com/index.php?showtopic=52145
Basically a simple way to do this, a short version of my guide for you, go to my network places, run network setup wizard on both computers, use the home setup, name the workgroup the same on both computers.
Next is to make sure that your firewalls are setup so that they do not block
incoming requests from your network.
Finally if you want to share folders/drives just right click on it and choose sharing, share it.