Some ISPs register the MAC address of whatever card initially sets up with them. You may have to contact them and provide the MAC of the new card. Usually, this is done at the modem level, so you shouldn't have this problem, but you never know. Anything's worth a shot at this point.
Make sure that your wired settings are also allowing you to obtain the IP from your ISP - Which is probably the case with your wireless. Should resolve what you're seeing.
And always remember to the correct power cycle in the event of reset. Modem, wait for it to come on completely - and then computer.