There are too many variables. As for not having permission to access another PC on the network, that's fairly simple if you create accounts on both with the same username and password. Another issue is network name and IP addressing. Each PC needs a unique address on a range of addresses that defines a network. You need to see how you have them assigned. If you have a router that can give out dynamic addresses, that works. If not, you have to give each device an address. You also get to deal with firewalls. These can come from Windows or third party security type software that will block data unless you tell it not to for your local network. Another issue is whether you use XP Home or Pro or a mix. Handling of permissions is a bit different on the two versions. Maybe if you gave a bit more information about Windows version, routers, etc. That might help get answers to narrow down the causes of your problem.
I have a wired desktop w/ XP and a wireless laptop w/ Xp also. Both can connect to the internet just fine, but I can't get them going together on a home network to share files and printers and the like. My desktop can "see" the laptop, but when I try to connect to it it says that I don't have permission, and the laptop can't even connect to the wireless network at all. Can someone please give a step-by-step detailed guide on how to set up a home network, or tell me what I'm doing wrong. Thanks for the help.