Siemens 4100 modem not working with Vista

I can't get my Siemens Speedstream 4100 Modem to connect to my new system with Windows Vista. My computer seems to recognize all of the internal hardware, and can see my wireless router, but can't connect to the internet or (apparently) the modem, even when I direct-wired it via LAN cable.
I have tried everything, including disabling Firewall, and it just doesn't seem to be able to connect.