Have you actually set at least one folder in each PC as "shared" by right clicking it and selecting the Sharing & Security option?
As there is no internet involvement, have you allocated IP addresses manually to each of the network adapters, rather than letting Windows allocate addresses in the 169.254.x.x range which *may* not work?
If you are using third-party firewall software, it is probably better to configure it properly to allow access by networked computers, rather than disabling it. I'm always a bit sceptical about whether "disabling" firewalls does actually render them completely ineffective.
Have a look at this article about "client" access when accessing an XP Pro and the need to be logged in to both PCs with identical Usernames/Passwords. - click here