From firewalls to account issues you get to research each area. Your post is good but what I find is that folk don't want to be an IT guru.
Try no firewall and enable the Guest account on XP. Since both steps are widely documented, I'll stop here.
I have a new LG 50PS80 plasma tv. I can, hard wire, connect the tv to the internet through my router. I have two desktop PC's connected to my home network through the router. When I get into Netcast>My Media>Network>it shows both pc's in the network. When I click on one of the Pc's, it shows all the photo files on that PC and I can view the photos. When I click on the other PC, it lists all of the photo folders on that pc but, when I try to open tha folders, I get the msg. "Failure to view folder". Both PC's run XP Pro and are in the same workgroup on the network and have file sharing enabled on each folder. I have tried everything that I can think of but can, still, only view photos from one pc. I would appreciate any suggestions.