vista xp network

Hi I have had no luck trying to get vista to network with my xp machine ever since I installed vista. I have tried every suggestion I found here, in this newsgroup and in vista's help, with no luck. Sometimes, after I change the workgroup name from MSHOME to WORKGROUP or from WORKGROUP back to MSHOME I see the xp machine showing up in in network center (NC) while NC is opened. When I close NC and re-open it the xp machine is no longer there. While the the xp machine is the in the NC, if I try to open it I either get a "network path cannot be found" or "Access is denied" messsage. If I run the diagnostic tool it reference to something about a wireless network. Neither computer have any problem connecting to the internet via my router, but to each other - no luck. My install was done as an upgrade over XP. Also, AOL is not working. I even uninstalled AOL's Port Magic without any luck with my home network. And when I tried to reinstall AOL's Port Magic vista would not let me. Any suggestions