Well you can double-check your method of port forwarding here: http://www.portforward.com/routers.htm

Oh I just remembered (I also use a D-Link but for mac), did you reboot the modem after your port forwarding? This is a must.

Re: Toshiba, well I couldn't find anything specific. Just (a) http://www.cablemodemhelp.com/pcx1000.htm & (b) http://forums.modemhelp.net/viewtopic.php?p=12872