How to connect a Win XP Home to Vista & Win7 Premium via Workgroup?

I have a Win 7 premium, Vista premium and an XP Home, all laptops that I "tried" to connect via a common workgroup name. The Win 7 and Vista can talk to each other and both see the XP Home laptop (the XP Home laptop displays in the Network window), but neither can access the XP, and the XP cannot see the Vista or Win7 laptop. When clicking the XP icon from either Vista or Win7, a dialog window displays: "Can't find computer, or computer name is not valid, make sure it's connected to the network, etc, etc." All 3 laptops are connected thru the same router via wireless connection and all can access the Internet. Could it be that the XP Home is such a legacy OS that cannot be integrated into a Home network/Workgroup. That would be crazy. Has anyone an idea? .