I have two computers and an ADSL moden connected to a hub, and the computers can independently connect to the internet, and both have the same version of windows XP installed.

I tried setting the network, specially because the computer downstairs doesnīt have a cd-rom and I need to share it. When I was almost done with it, I go the message that Windows does not recommend the kind of network I chose because it is not safe.
I tried then, the option "This computer belongs to a network that doesnt have an internet connection", even though I have one and thus I believe it wont be safe the same.
Anyhow, it didnt work. The computer downstairs recognized the one up here, but couldnīt access it, while this computer didnīt find anything.

Also, the fact that I canīt undo the network, and that I can redo it over and over again without getting the message "you already have a network set up mate" is really not helping at all.

The help I found on google and here did not apply to my case, most where saying things about needing a NIC. So, any pointers? Do I must use the unsafe option and set up firewalls that, as Windows said, might make sharing files impossible sometimes?