No connection could be made

Hi,
I have a problematic machine: In my home, there is a Mac-overweight, and therefore stands around as an AirPort router. I can with my now 4 year old laptop which is not wireless internet, so even though the network is detected. After giving the password I will get the message "no connection could be made …" Does anyone know how to make a connection to a Mac-router at all possible ways, and if so, why my attempts that fail?
Information on the PC:
HP Compaq 6910p
Network card: intel r 82566MM Gigabit Network Connection
Thank you and best wishes!
