Ok, now i managed at least to connect to the windows. You have to know the IP (i forced to apply one) and then in the connect to server window digit smb://xxx.xxx.xxx.xxx. You will be then asked to input name and pass (must be a valid account on the windows machine). From that point on the window computer will be in the shared computers list and all the shared folder within will be accessible. Still haven't been able to do it via workgroup.
And here's how i connected to the mac from windows. Quite the same. On the mac you have to open system preferences,sharing,enable document sharing,click on advanced button,enable sharing through SMB; you will maybe have to uncheck and then check again the user you want to allow so that you will be asked to digit a password. Go then on the windows machine, create a new account with the same name and pass you decided to enable on the mac. Then you just have to add a new network resource. If the mac does not appear digit \\xxx.xxx.xxx.xxx (where the xses stand for your IP, obviously).
Maybe one or more passages are redundant and then not needed, but this is the way i've managed to do it. Hope this helps until someone that knows how the things are supposed to work will answer.
Happy sharing!
